My takaway is that you need to define your fitness goals carefully…do you want to be group ride fit and smash it with the gang and impress everyone with your ability to fly up the local hills, or do you want to be able to hit 4 or 5 1000m+ climbs in a 8-9 hr ride?
Unstructured volume will contribute to those different goals to a different level. Right now I’m targeting 2 long hilly sportives with fairly short but steep climbs (up to 20%) followed by a week in the Dolomites with lots of long 8-10% 10-15km climbs day after day, so the current plan is loads of volume but more polarised with an emphasis on easier and longer rides and vo2 and longer threshold work interval days during each week to prepare me for the specifics. Nearer the summer I’ll start to do these intervals during long rides. So, more structure to my unstructured volume!