Thanks @MikeMckinney Chain rings and cassette are fairly decent condition. Not much wear, but I will take another look, just in case I have missed something.
@Michael_Brooks All have been dry rides (thankfully). And a bit of indoor turbo use.
@Thomas_De_Kesel Gosh 150 miles, that is 2-4 rides! I guess teh problem is, that with wax, it is harder to assess chain wear, as teh wax takes up some of teh slack (more so than oil I would imagine). However I will swap chains and (see if I can) measure the (apparent) wear on the ones I have taken off.
General consensus seems to be - 1) check other wear and 2) yes change more frequently - esp. is they get wet.