For my geared bikes: Chain off, into old milk bottle 1/3rd full of white spirit, shake it about a bit, Leave while I scrub other bits with old washing up and tooth brushes and soapy water to get the shite off, shake the chain about a bit more, leave for longer, eventually pull out, clean/off and shove in jam jar of oil, shake about leave, shake about some more (ideally leave in that over night if I’m not using the bike the next day), shake some more…
Retrieve chain, wipe off excess oil and refit,
maybe once every 4-6 weeks or so… DH Bike chain has been sat in white spirits for about 2 months though, so it should be really, really clean by now…
for the SS and Fixie I just smear more oil on the chain every other ride and possibly degrease it as above maybe once a year if its lucky…
Tried one of those chain cleaner tools, found it quite faffy and not very effective TBH…