At the beginning of every year, I invest a couple of days to go through the most beneficial books on training. This is to keep my memory fresh and to not miss out on important training factors for myself and for my athletes.

Tudor Bompa: Theory and Methodology of Training
Phil Maffetone: The big book of endurance training and racing
Jack Daniels: Daniels' running formula
Brad Hudson: Run faster from the 5K to the Marathon
Joe Friel: Triathletes Training Bible
Kelly Starett: Becoming a supple leopard

  1. Choose Your Race

When you plan out a training cycle, it is critical to know the date of races and what workouts to hit right on the head. I am not following race seasons. I most likely start out a a base and then slowly we see, when the time will come to stand on the start line. Sometimes feeling fresh, snappy and ready to go and other times feeling lousy and low motivation. This can be a difference between an 8 week and a 16 week training plan. Flexibility is already present. For pro runners paying a double race entry early in the season is no problem, maybe even to get free invitations. This is the way to go. In this case, if the runner is not ready, he can do a a full or partial tune up run, depending on race distance, during the first event. See what is going on, adjust and correct and be perfectly ready for the "A" race. The proceeding cycle can include more training, more specialisation or way more rest. I prefer to not to do this on back to back weekends, but 4 to 6 weeks apart. Of course the ideal would be having back to back weekends and another one 4 to 6 weeks apart, but this costs a lot and can cause a lot of disappointment in the event organisations and might very negatively effect your palmares.
This would ensure that peaking is very finely tuned and opportunity is not missed. We are ready, but if race nerves, food poisoning, or any issues come up, next week our peak is still there. Otherwise, postpone all to the final race.
Either ways this is the very first element of structure. The date of the race.

2. Fitness Test

The second element would be one or two fitness testing workouts. In case of trail running it would be 10 / 15 / 20 days out, run segment timing on race course. In road running, race pace training is advised by most coaches. For a 10k, running a 4 x 2000 @ race pace /w 1min recoveries and a final 1k faster than race pace is advised by Brad Hudson, 10 days out. We can see very similar approaches in other coach's programs too.
For ultra runners, depending on race course, mimicking a section at race speed is a great indicator of fitness. If it was high mountain, very long distance ultra running, back to back or 3 days in a row, segment training is advised, probably 3 weeks out. Long days in the mountains are very taxing. For a multiday constant events like Tor des Geants or the Swiss Alpine Challenge, sometimes 3 x 10hours on consecutive days are prescribed, with race gear and proper nutrition. Of course in the latest case, mostly we talk about speed hiking, not constant running.
For big multiday, but non-constant events like the Costarican Trail or the Marathon des sables, the approach is very different as the length of days are very different, the terrain changes extremely a lot and as days go by, your pack get's lighter and lighter. A full event training is possible, except that the long day should be cut or excluded. Run/hike a 20/30/40/30/20km week is possible for advanced runners, 5 to 8weeks out. That will give you a great idea about your pack, your clothes, your shoes, your body and mind and your recovery ability. On the other hand we can see runners succeeding in ultra events on longest runs shorter than 15km. Individuality and personalisation !

3. Race pace practice

The first two data points were, Race day and Race condition testing. If you were a first timer, honestly your objective is finishing. No time goals needed !
However starting at the second race of your life, time and pace can be projected. It must be surely a down to earth decision and a slightly moving target. Race pace workouts of short and longer intervals should be included already at the beginning of a training cycle. This is to show, that you need what ? Power, speed, endurance, speed-endurance, strength, resistance ?

4. Hills

I now hear from like the 10th coach that hill sprints, hill repeats and hill long runs are very regular part of training. I mean in and out of season on a constant on going basis. I include them too. On a weekly basis I give out and I do personally 2 hill session. If tired, it might be only 6 x 6 sec. High power, all out, perfect posture accelerations. If fresh, I might choose a slightly lower grade hill and add a 10 x 20 sec set. For weak athletes that would be a staple at slower speeds, not all out power sprints with an explosive start, but gradually increasing and decreasing pace to arrive to a 20 sec interval.
Depending on the goal race, normal hill efforts get maximised at 5 x 3minutes in structured training.

While you might spend hours in the mountains, I would not prescribe 4 x 10minutes uphill hard for most circumstances. If you were a road uphill specialist, that might be the case though, but it is rare. We have an uphill running circuit here on the South of France. It consist about 10 races and they are brutal fitness challenges. For instance climbing the highest mountain pass of the Col de la Bonnet. 26km D+1600m of gain to go up to 2800m. Or the Mont Ventoux, Col de Vence, Col de Braus, Ascension Gourdon, Ascension Mont Chauve and more. All on road !

The beginning 4 structural elements:

Race
Pre race fitness test
Race Pace Workouts
Hill Sprints and Hill Repeats

The rest you can fill up, with the necessary sets for your fitness and race readiness. This can be one way of building up your season and having it down on a paper. Your preparation might indicate that you are on the good way or you might totally derail from your complete plan. You might throw away 2 weeks of plans, to come back stronger and return to the written workouts and complete the cycle. You also can totally lay back, restart a very gradual base and come back to the start with a rescheduled race season.

Do not be rigid to plans. But do not forget that periodisation and specialisation is science and it works. When trying to reach a goal, there are no miracles. If never practiced 3:30/km race pace for a marathon, but this is your goal as you have a 35min 10k time, most likely you never run a 3:30/km pace marathon. However don't be scared if have the flue of a 16 week training cycle and have to drop 5days to heal. A lifetime of running and 15weeks and 2days will never be diminished by 5days in bed ! Just reinforced !