How often do you dismantle and lube derailleur sprockets? (jockey/pulley wheels)

[Carlton green]

I found the tittle (derailleur sprockets) confusing too and believe that the OP is referring to jockey wheels or jockey pulleys.
https://www.sheldonbrown.com/derailleur.html
https://www.wiggle.co.uk/jockey-wheels

Call an item whatever you want to, but using the same terms as other people tends to get the best results …

One - of many - benefits of using hub gears is the lack of jockey wheels to care for. When you do have jockey wheels then as best I can recall servicing was about twice a year for a bike in daily on-road use. Other than keeping them clean internally and externally I’m not sure what the best care of them is. I used a little light grease and oil (on the bearing surface) but suspect that their simple plain bearings don’t need either and just have a limited service life - those with sealed bearings should have a long and maintenance free life, but IIRC mine didn’t.

[Chris Jeggo]

I found the tittle (derailleur sprockets) confusing too and believe that the OP is referring to jockey wheels or jockey pulleys.

<snip>

I did not find 'derailleur sprockets' confusing because the derailleur is simply the device which 'derails' the chain, so sprockets on a cassette or freewheel block are not part of it.

So I took one of the sprockets out to find it has a sealed ball bearing, unlike my previous bike which had just a bush. So nothing to lube - just a clean up.

Is there a bit of confusion here about what a derailleur sprocket is?
Either it’s a pulley wheel (there are two) that is part of the rear mech
Or it’s a cassette sprocket (the derailleur moves the chain across them) mounted on the rear wheel.

No confusion on my part.
My understanding is that sprockets have teeth and are used for chains (or caterpillar tracks), pulleys have no teeth and are used with belts or ropes.
Cassette sprockets don't have bearings as they are fixed to the freehub.
The two Derailleur sprockets fit in the rear mech cage (Some people do refer to these as pulleys though) and have a variety of bearings.

+1

[Jules59]

I now realise that the common name for them is pulley / jockey wheels.
However it was not my intention to confuse but to be precise - but that obviously failed.
I used "sprocket" instead of pulley / jockey wheel as I was sure somebody would inform me that they were in fact sprockets (re teeth and chain.
https://en.wikipedia.org/wiki/Sprocket

But the important thing is that I dont need to lube mine now.

Interestingly neither "Jockey" or "pulley" is listed here, but neither is sprocket
https://en.wikipedia.org/wiki/Glossary_of_cycling