Sounds like you're dialing it in. I think as you gain experience you won't need as much pre-shave. I still lather in sections so that's something that might be good to carry forward.

If your shave is mostly nick free then the alum won't burn. I suppose you could be allergic but it sounds more like you just had a better shave.

Really the biggest trick is getting a feel for resistance and pressure and it sounds like you're getting closer and closer to the sweet spot.