I've ridden rollers quite a lot before and much prefer the feel of them to turbo trainers, plus the stressful part makes it more interesting
With regards to training on them I usually just make up the session as I go along which is fine but I thhink/know that there must be some specific training sessions I can do to help me improve fitness and strength.
Have a same feeling about it. I couldnt stand my trainer - even 1 hour was amazingly taxing on my mind and I felt sorry for my carbon frame. It had to go - bought myself more winter stuff and remind myself rule number 5 constantly. Recently I have bought Elite Arion Mag Rollers and the sensation is completly different. It is no fun for sure - but couple of Sufferfest video and time just fly, also the balance part makes it more interesting. Also my riding efficiency went up thanks to smoother pedal stroke.
Anyway, if Im time crunched I usually do 2x20min 90-95% FTP on rollers. Since it is winter I do 4-5 hours ride outside. Mostly in Z2 zone. The less time I have for a ride the higher the intensity. But usually I do intervals inside - keeping the variables out of equation and frankly I dont have a powermeter on the bike.