I don't borrow or loan out my lights. Selfish? I don't think so. If I borrowed another's light and somehow I broke it or dinged it, I'd feel lousy. There are few folks in my area to whom I'd loan one of my lights who also had any idea of the cost of the light. If they damaged one of mine, I'd feel they were responsible and yet I might feel guilty in having them repair or replace the light--some really can't BE replaced.
Timeframe for lending? If you have to ask for it back, it's been too long in the hands of the person to whom you loaned it. Now, I agree with setting some timetable fot the return but that may be difficult. What's
"reasonable"? I dunno.
Too short a period of time lent might not allow the person to actually use the light and, too long and they may think it's been a gift of sorts. Therefore, I don't borrow or lend...
Karl