I also have a microbush. Yes I typed that with a straight face In the first few years I tapped, I did try to rotate, as much as possible, through my 8 tappable trees (they are all big mature 3-spilers)...First couple of years, I only tapped two trees, then two different trees, and so on. But since 2013 have settled on 6 trees, and now put in my 18 spiles each year in those same 6 trees. I also am somewhat OCD and keep a daily log as to how much sap I get from each tree, each day. That makes it much easier to track flow and anticipate when to brace for a big run.
In terms of the *health* spiles...yes, they leave a smaller hole. But some of my trees are slow to close up holes of any size, from even 4 years ago, while others close up easily within 1-2 years. In those trees, the health spile hole from last year's disastrous experiment are just as slow to close. I watch each tree like a hawk all year round and note how healthy the tree is, is the canopy nice and full, is it showing any sign of infection or weakening, and if anything, the trees I tap with the big ol 7/16ths are in much better health than the trees I DON'T tap!!!!! But, if you can drill holes for those weeny little health spiles just right, so that they actually stay in and don't just fall out of the tree (as they all did last year when I tried them) go for it!
Been tapping since 2008.
2018 - 17 taps/7 trees...819l sap, approx 28l syrup
2019 - 18 taps/8 trees...585l sap, 28l syrup...21:1 ratio
2020 - 18 taps/8 trees...890.04l sap...gave away about 170l, 30l snafu'd....23l total for me from approx 690l
2021 - 18 taps/8 trees...395l sap, 12 l syrup
2022 - 18 taps/8 trees....7 sugars 1 red due to #2 having surgery so had the season off....582l sap, 18.5l syrup
2023 - 18 taps/8 trees...all sugars again. 807l sap, so far approx 14l syrup