If you make a sudden gain so big that you shift your RPE by a whole power level (don’t say zone, it offends Dr. Coggan…), there is no scientific benefit to doing your existing plan!
I found myself doing an HOUR AND A HALF on the road without significant discomfort at an NP equivalent to what my SST base training plan had me doing for 8-10 minutes at a time. At that point it might as well be a high endurance or low tempo ride.