So, stupid question, but my friend told me that you were never supposed to take the strings off your bass, because they would not be reusable. I took the strings off my bass
Now, I wonder too, what your friend has been smoking? How the f*ck would you ever get your bass serviced then? Say you have these unwieldy truss rod where you have to adjust relief by even removing the neck for the allen wrench to reach down, then you have to re-string and tune up and see if the relief was ok. If it wasn't just re-engineer it, and you have to take strings off and on as many times you like, before it's set and done.
Re-use the strings as often as you like. You probably know when it's time, and nothing helps getting them in shape again. You'll hear and feel it.
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I wonder where all these myths comes from? On WikiHow there's one section - albeit guitars - that says "you shouldn't take off all the strings at once" and the other "if you store your guitar for a longer time, it's best to remove all the strings". Beats me. When confronted with this paradox they just go .... blush. Remove and take off the strings as many times as you like. And re-use them. The metal fatigue up at the tuner part will take its toll eventually. But if you're careful and use the same "knick" and bendings when you re-string them it's no problem.