One time I tried going up from 0.05 to 0.1%. I applied the 0.1% one night a week for a 8 weeks. Then went to twice weekly applications after that. On the other nights I was using 0.05% the whole time. But my skin just would not adjust. The flakes and redness would not subside after almost a year of alternating using both strengths so I quit the 0.1% and stayed with the 0.05%. The 0.1% was not meant for me.
You don't have to peel to benefit from using tret. Peeling is a side effect on the surface of the skin. Peeling/flaking is not an indicator of efficacy. Where the action happens is beneath the surface, not on top. Occasional light flaking is normal but excessive flaking/redness/inflamed skin is not.