Because the pump inlet is offset to the pickup loosening or tightening the pickup will move it up and down in addition to side to side. Maybe I'm lucky but in 35 yrs. of working on them I have yet to have a problem setting the pickup gap level within 1/16" and with the proper gap to the sump floor just by adjusting it. If it's angled front to back that's a different story but I haven't ran into that either. I don't use teflon tape for the reason you mentioned. High temp pipe sealer is what I use and I adjust the pickup height right after installing the pickup in the pump before the sealer sets up