Mine are very simple compared to what im seeing but it works for us (7 mowers, 4 trucks)
There is one for mowers and equipment such as skidsteer/tractor and a seperate one for trucks. They are spreadsheet form. We fill in the hours service was preformed and any special stuff "rebuilt transmission" goes in the Notes section at bottom.
Blade sharpening and grease are done so often I left them out of the sheets.
Im going to go through my system next winter to better track the maintenance of all the handhelds, push mowers, trailers, etc. Hard to believe winters almost gone! I had plans to do alot of "organizing and system building" this winter. Alot will have to wait.