Servicing basic hubs - usually pretty simple - front needs a 13mm cone spanner, rear a 15mm, both plus a 17mm for the locknut. But no, pair of wheels from a Specialized bike needs 2 off 17mm cone spanners . . . and who has more than 1 of each of the cone spanner sizes? Not me, I have a complete Park set from 13 to pretty big, but just one of each.
... and while I'm at it - there must be an easier and less messy way to refill a Park Tools grease gun from a bulk can of grease . . . I have to use a flat tyre lever to spoon the stuff in, press it down - and repeat - then a home-made tool (bit of seatpost tube) to push the inner cap up to create the pressure. Aaargh! Oh, and a bigger gun (more grease) would be an improvement.