That "slow trickle" part is the key detail that most people miss, and I'm glad you brought it up because I've seen folks wreck a trunk by going full blast. I feel for you on those deep planted maples, I've dealt with the same thing on a few jobs and it really does eat up your whole afternoon if you go at it with a shovel. Water is the way I do it too, though I'll sometimes just poke around with a thin rod first to find where the flare starts before I even turn the hose on. Sticking a screwdriver or a metal probe in and feeling where it stops going in easy tells you a lot in about two seconds. The hard part with silver maples is they send those surface roots out everywhere, so once you wash the dirt away you have to be careful not to leave them bare for long. Sounds like you got it done right though, and 10 minutes beats 40 with a shovel every time.

Saw a thing from the Cornell Lab a while back about yard lists and the average suburban yard in the Midwest gets something like 120 to 160 species over a few years. So you're right in the normal range, which is kind of wild when you think about how plain a yard looks. Migration is where most of the magic happens, those random warblers and thrushes drop in for a day and vanish. My neighbor keeps a list too and she swears by putting in a small water feature, says it pulled in stuff she never saw otherwise.