I wrote the following for my existing clients and primiarly the online portion was who I had in mind. In person training I have a little more control over these outcomes.
It's not uncommon to see people skip out on the last week of a training cycle (typically week 4/5) in whole or in part after 100% adherence up until that point.
That final week with the RPE of 9-10 (high rate of effort), it should easily be your max volume week. With 9-10 effort you'll likely be completing maxes with weights you haven't used before. Essentially, that last week is what you're building towards. It's common to start feeling worn out by then after a month or so of work but then the reset always comes. If you happen to be dieting to lose weight (calorie deficit) while I'm simultaneously building the training volume up then you most certainly shouldn't feel 100% fresh by week 4-5. Normal.
If you're primarily doing strength training (heavier lifting, 3-10 rep range), the same applies. You're starting out probably close to 75-80% of your max effort and by week 4-5 you'll be up around 95%-100% on the big lifts. Fatigue accumulates but essentially it's like running a marathon and then stopping with 15% of the race left if you don't finish off the final week.
I've found clients as a whole are usually reluctant to do DELOADS but then take a break at some point within a training cycle anyway. I will start being a little more adamant about deloading every 4-5 weeks if you're working out 3-5 days weekly.
A few other things you can do to extend a hard training cycle on the back end if you're feeling the drain...
1) Push a workout (or the workout week) by a day or two (not a full week). It may get a little confusing in the spreadsheet but we can figure it out.
2) CARB load. Extra Oats/Bread/Rice/Pasta/Grain Cereal. This is for energy/recovery to replenish glycogen stores. It will not help you lose weight but it'll likely boost performance and act as a pick me up. You'll likely get a temporary weight increase.
2.5) Combine #1 and #2. Take a bonus rest day and carb up. I typically only do it when I'm gaining weight (but it can be done in weight loss phases too) but I've pushed a workout and then ate an entire box of cereal on top of my normal food for the sole purpose of replenishment for training.
3) Caffeine....You likely don't need caffeine when you're maintaining body weight but would be worthwhile deep in a training/weight loss cycle. Maybe consider eliminating caffeine from coffee/tea/soda and utilizing it as a performance enhancer prior to exercise.
Obviously sleep, diet, rest, stress all factor in strongly to how fresh you stay throughout a training cycle but assuming that stuff is locked in fairly good, the above would apply.
I feel like this is solid information that was worth sharing beyond the client pool.