I have a circle and a strip of PTFE-coated liner cut to the size of the tins I use most often. The circle just gets used in one tin but the strip works for about 4 different tins (2 sides and base).
Usually I don't faff about lining the sides otherwise, but lining the base helps.
If I need a greaseproof paper circle cutting for another tin I get a child to do it - at 5 and 6 it's something they can manage to do and it's less messy than involving them in other aspects of cake preparation.