One of the downsides to owning over 40 stringed instruments, is that every so often they need new strings. Particularly the instruments I use regularly, which I like to restring every couple of months.
Why do you need to change strings quite so often? I hear you ask. Well after a fairly short time strings get dirty, oxidised, and clogged up with dead skin from your finger tips. (Gross huh .... bleugh!) Also the oils from your skin gets into them and this all makes them sound dull, dead and lifeless.
There are various products available that can be used to clean the strings, but I find this just extends their life span from 4 weeks to 8 weeks.
So as you can imagine 40 instruments cost a lot in new strings and take a long time to keep them all in good playable condition, as a restring, clean and set up of an instrument can take best part of an hour.
But it's worth all the expense and to time as there is nothing finer than good instrument with a fresh set of strings on.