While i don’t lift my bass by the individual strings when installing new strings, i do pull them really hard. I sit in a playing position and with the strings tuned to pitch i grab one string at a time (starting with the E) right over the neck pickup and pull them away from the bass pretty hard. Once i’ve done all four strings i’ll retune, noodle for a few minutes and do it again. After about 4~5 rounds they are pretty much GTG. Oh and almost forgot DO NOT let just them go when you have them stretched out like that, keep holding them and let them go back to their normal position.When I put new strings on my bass, I literally pick my bass up by one string at a time and shake it back and forth.
Yes, you are reading that correctly. I grab my A string, use it to pick up my bass out if my lap, and shake it back and forth.
The only one I can't do that with is the G. But I still yank that string around quite a bit.
Instant break in.
Not joking.
While I don’t pull near as hard for this, it is also a simple way to bring your pitch down if you happen to slightly overshoot your mark when tuning.