This is particularly important at the initial state where you're eroding down to a level - when you're just going through grits smoothing it matters somewhat less.
https://youtu.be/WtExoSMgvXI?t=260
These guys are sanding down the mobile CPUs and soldering jumpers to do a password reset. I didn't know this was even possible.
Much easier when you can let a power tool do most of the work.
Best part is that ad blockers work all over the world, not just in the few corners where YT designs to let you pay to skip ads.