We normally put the bathing tabs every day in spring, summer and autumn. In winter since there is less light, we do not always manage every day but what was interesting for us to see, is them having a bath, when they are surrounded by snow!
As a general rule of thumb I would say, that you should give your canaries the possibility every other day to have a bath or minimum twice a week.
The baths should be always clean and you should use fresh water to fill them up. Around a finger deep would be enough for them and then they can enjoy their bath and you can enjoy them “dancing”! That is how it looks to me!
Here Mira and Seb having a bath:
Again Mira here:
Yannis and Stella @Apollon, Naxos 