My current training regime (via PILLAR AI coaching app) is polarised. What I can say is that I'm currently smashing all my PRs at the moment, without even trying to. Basically off a diet of short VO2 max 1 hour interval sessions and 2-3 hour strictly Z2 endurance rides on a 6-7 hour total week. Almost seems too simple, but it appears to be working for me. It will be interesting to see how my century events go this year. Hopefully I won't fall apart after 3 hours!

Edit: Previous winter I was doing a lot more variety of zone intervals and an average volume of 10-12 hours per week.