Is it not quite rational that some days will be better than others? I play a bit of tennis, and some days cannot serve for toffee, other days they come good.
Many days I start off the day with a couple of training runs. Just to do nothing other than do a few drills, and keep reminding myself of the basics.
However, in skiing, the environment often has a strong, and sometimes unseen, impact. You may start the day, having an "expectation" of the piste ground conditions, based on the previous days skiing.
But overnight, a number of factors can contribute to several changes in the surface and substrate crystalline condition. Ise is your man for the detailed knowledge, I just know it happens.
You may have already identified a technique issue, ie weight forward. First thing in the day, the surface is glazed, and Whoosh, you spend the next kilometre trying to catch up with your feet.
Oh, and stay off the grog the night before.