Really the only intervals I've consistently done over the past few years have been 4 to 6 x 4' @110-125% depending on the day.
Cat 4 to 3 year I did 4' intervals, 20' intervals and 80" intervals but I don't think I was rested enough. Then last year I rode rested more but mostly just long rides with either 20' climbs or vo2 at the beginning. This year so far I'm trying to get hours in between the rain and figure out the new roads. But making sure to hit some unstructured vo2 during the week and long rides with threshold climbs on the weekend.
Maybe I just have to add a midweek threshold workout for a while.