If I'm jig fishing usually 6 feet or so. If you bust off a jig you still have plenty of line to tie another jig back on...
If rig fishing 15, not because you need more line when fishing a rig, it's because that extra line is used to tie your next rig when you break off without having to tie a new leader on. The rig I use is the Belmar Rig and it takes a fair amount of line to tie since the last foot of line is doubled.
https://www.njfishing.com/forums/showthread.php?t=78024
