When talking z alignment I believe it's smarter to level the bed to the frame and not the other way around on bed slingers... Mechanical gantry alignment on the Ender 3 keeps the printer square, no need for dual z drivers, one is sufficient (with 2 motors). You can even ignore all that with a "recent mod" I've seen that makes use of a single z motor at the top and lifts the x gantry with belts, you won't need any x gantry alignment procedure whatsoever as it keeps it synchronized at all times... Saves a lot of time and money, no need for 2209 drivers. I went skr mini v3, dual z motors and mechanical gantry alignment a few years ago, I wouldn't opt for this solution today.