Is it just the nature of the beast?

Take Care
Steve

Anyway, this is typical of the N, but here are some things you can do to reduce/eliminate the problem (in addition to having everything tuned up properly):

Use copper core plugs wire, not standard off-the-auto-store-stuff. Keep wires away from each other as much as possible. What happens is arcing from wire to wire or to other grounds causing weak/no spark. If you run the tractor for awhile in complete darkness, you will even see some tiny sparks flying across the wires.

Re-check timing too when engine is warm (4 BTDC).

I was having intermitent misfiring where I'd had none before. Went thru my entire ignition checklist and was baffled until I happened to have the rotor in my hand and was absentmindedly pressing the spring down with my thumb while contemplating my next move. Replaced it and no more miss. Sometimes the simplest things cause problems.