That bandsaw edge also means the hinge side is the one side you can trust to be square, so the real trick is knowing which side of your filler faces the wall. Grain direction matters more than most people realize when you flip a filler around.

Wait, how did that first session even go down? Like did you show up not knowing if this guy was legit or a total weirdo, or did you talk on the phone first and get a good vibe? I'm asking because I found a card once for guitar setup for ten bucks and the dude turned out to be some hoarder with cats everywhere, so now I'm scared of handwritten flyers. But a retired jazz guy who just wants to jam at 3AM sounds kinda perfect, honestly. Does he actually know his stuff or is he just noodling and you're both laughing through it? And do you ever bring sheet music or is it all by ear?