When you've spent any amount of time running RPGs, you inevitably learn a lot about yourself as a person, as an improviser, and as a project manager. Or at least you have some suspicions about yourself confirmed through play. So it came as little surprise to me when, after running one-shot sessions of Low Fantasy Gaming, Colonial Gothic, and The Sprawl for one group and starting a longer D&D 5th Edition campaign for another group, I realized that I wasn't so great at storing and juggling a large number of system rules in my head while also presenting and arbitrating over a fictional environment. Giving me access to the rulebook during the sessions didn't help; I struggled with trying to do more than a quick, cursory search for a piece of information.
I thought back on my younger years. Did I really do that? Spend a lot of time just paging through myriad D&D books, searching for all the detailed rules? Did I derail a few dozen immersive moments each session to check on minutia? The memories are hazy and I'm left unsure. Maybe I wasn't tuned in enough to the dramatic potential of immersive gaming to notice; maybe I didn't look much up then either.