Cycling Fitness / Training Advice

I’m planning on adding 1h at mid-high zone 2 at 90-95rpm every morning before breakfast, see whether I can build a higher level of fatigue resistance.

I would be interested to hear how this works for you.

I’m better setup for weekday very short rides (1-1.5hrs) this winter. I’m lucky I do have some good roads for training (inc a TT course just up the road).

I need to build ‘base’ but have no idea how to do that with these short rides. Just ride everything just below threshold? Who knows.