Hardly ever. Just after or during rain shower. Just rinse with lots of water and soft cloth/brush. Leave to dry, don't rub. No need for detergents or cleaners, apart from removing the occasional tar spots - not seen so much these days. A dab of petrol or white spirit is all you need for these. In winter don't bother with anything above waist line unless visibly dirty. Polish very infrequently.

Like John-F, I wash my car off when it has been rained on, so that any dusty stuff should be too soft to make scratches. In a prolonged dry spell I just keep the glass clean so that I can see out. If you have time to burn and like looking at a polished car, do that too - or you can pay the east Europeans to do it for you. But don't forget it isn't their car so they may be less careful than you.

You'll get enthusiasts telling you to use the two bucket method, clay bars and unobtanium car polish and wax.

The greens will tell you not to use microfibre cloths as they shed micro plastic.

I use a soft brush on the end of a hosepipe and a chamois leather - that'll get the detailers going. NEVER re-use anything you drop on the floor until it's been thoroughly cleaned of grit. For the same reason be careful about letting kids help - they will drop things. I also give the wheel arches and underside a good hosing, the muck that comes out will surprise you. I've got something like a glass cleaning brush to get in the nooks and crannies of ally wheels. The lockdown gave me an excuse to use some of the polish and wax in the garage I've been gifted over the years, hard work, but it makes washing the car much easier, perhaps I'll do it again in another six years.