Every time I ride. At least on the “A” bike with supple tyre sidewalls and light casings. And among my general 50 - 50 mix of road and tracks / bridleways in the flinty chalk of the Yorkshire wolds, where sharp grits are prone to embedding and puncturing just about any tyre compound.
Local, rural rides on the “B” bike with supple tyres - the roads are pretty clean generally - except for beer bottle glass now and then. Chucked from moving cars no doubt. Worth stopping to have a wipe of the tyres then, with a handful of verge grass as a rough brush, maybe.
Utility hack wears Marathons. Never look at these. That’s tempting fate. Nexus hub, so I will pack my spanners and scabs next ride.