One of the old guys on the field keeps a box of plug washers that he anneals when he has a chance. When in a hurry I give him my used washers and get annealed ones in exchange. That gives him the opportunity to call me lazy, so its a win-win 
In reality you can obviously reuse them several times, but replacing them is part of the ritual.
On my four cylinder Lycoming I use the ‘car style’ alternate Champions (REM37BY) and like them – they don’t foul and they can be re-gapped easily if its necessary.
Last week I watched the Champion (massive) plugs come out of an almost brand new (40hr) Lycoming IO-360 that was getting a plug misfiring on the ground.
We tested them and 4 out of the 8 were open circuit. Tempest have gone back in. No more misfire.
Personally I wouldn’t fit a Champion plug in my lawn mower
Personally I wouldn’t fit a Champion plug in my lawn mower
These are neither ‘massive’ nor ‘fine wire’ by conventional definition, but they work pretty well, honest
