It sounds like you already recognize it, but building fitness is not a linear path. That’s true at the micro level (3-4 weeks blocks) and at the macro level (over the course of the season and multiple years). If you want to get stronger long term (over multiple years), the proven approach is to target peaks during the season, but then allow your training stress (and fitness) to drop for a bit before starting to work toward another peak. This gives your body the chance to reboot, particularly hormone levels and things that are affected by long term accumulated stress.
The following chart shows my training load and stress balance over the course of the season. And I’m not saying this is the right approach for anyone else, just what has worked well for me. I targeted peaks in late May and early August. The only time of the year I was aggressively ramping training stress was January through early May. Between May and August was more about shedding fatigue and then a small rebuild to hit the highest performance possible for the 2 peaks. The rest of the year, I’ll still race, but not at peak fitness and certainly not ramping up training stress. I could certainly try to do a 3rd ramp/build later in the year, but I’ve burned most of my mental and physical motivation once August rolls around. I’m a big believer in “make the hard stuff really hard, make the easy stuff really easy. For me, that’s not just an approach for workout to workout or block to block, but also how I treat the entire year. Throwing everything I have into a really aggressive 4-5 month plan results in better race performance than going “sort of hard” for 9 months of the year. But that also means that I’m not fighting for podiums in my fall races when my fitness is lower and I’m basically de-training (so I can start strong/fresh again in January). Again, not an approach that’s right for everyone, but has worked for me. I turned 57 this year and hit power PR’s for everything 1 hour or longer. FTP peaked around 315 (which I’ve hit in the past), but my ability to hold a high percentage of that for long durations is what I’ve seen continue to improve year over year.
If I were you, I’d try adjusting your plans to take more aggressive CTL swings up and down over the course of the season and see how you respond. A slow and steady ramp isn’t wrong and can be very effective for a time, but at some point it’s just more of the same and you need to interrupt the pattern and introduce a novel stimulus to drive more/different adaptations. A big part of this approach is putting the ego in check for much of the year when you aren’t in top shape.