I've been GMing tabletop games for years now on a pretty consistent basis (roughly once a week!)
And maaaan I still sometimes feel like absolute dogshit about how I did. Like did I let my players participate enough? Have I put the spotlight on a single character too much? Am I making the game more about the NPCs? Is my combat going too slow? Is there too much combat? Not enough combat?
I fucked up a scene last night where I had to back out and just like redo everything because I totally ruined the pacing of it. That was rough :(
