My mom insists than whenever I don't use a sewing machine, I have to put a piece of scrap fabric under the sewing foot, lower the foot and move the needle all the way down. This is supposedly true for all machines of all manufacturers.
When asked for the reason, she couldn't answer me. "It just is that way".
I can understand the advice when moving the machine to avoid accidentally bending the sewing foot and needle, but otherwise this doesn't make any sense to me.
Is it true (or was it true in the past) that you should lower the foot and needle of a sewing machine when it's not in use? For what reason?