If you don’t have any races planned for the year or a specific event and your main goal was to stay fit and strong for club rides what training phase would you do? Would you still go through all the plans (base, build, specialty) or just keep repeating a specific phase or two?
If you weren’t doing any events, I would train in a way that stops you getting bored and that keeps you motivated to keep training.
I think you can be as flexible as you like, so long as you do a ramp test every 6 weeks or so to ensure you are still getting workouts at the right intensity.
If I were in your position, I would consider entering some new events. Perhaps do a few Time Trials or a long ride, or some Cyclo Cross races or even a mountain bike event or two.
Something you haven’t done before that will keep things fresh and interesting.
No, you’ll lose interest. Do the group rides, use these to see where you might have weaknesses and use TR to try and deal with those.
Sweet Spot Base and General build are easy options. Enough variety to include various energy systems and maintain fitness, with the ability to work through the spectrum of demands.
You could simply repeat those or swap the Build for a different one each time for variety too (Sustained or Short).
Do a Specialty if you want and lick anything that looks fun or challenging.