Buttholelane My dogs only have their teeth done once a week some weeks and theirs are lovely and clean. The Plaque Off stuff is great for getting rid of an exisiting build up, it seems to soften the tartar so you can just scrape it off and it also comes away with hard/rough chews.
We had to do it several times a week at first, but now twice a week for maintenance seems to keep them clean no problem, which considering how bad they were is amazing. We do scrape though, instead of just brushing and I'm lucky that both of them are compliant.
I do think it varies from dog to dog and breed to breed though. Some dogs seem to suffer far more from tartar and dental issues than others and some seem to get away with hardly any dental care at all.
I asked my vet if I should be brushing twice daily and she said in an ideal world, yes, but admitted that she doesn't manage that with her own dog and for her, like us, it's more like a couple of times a week, which works for them too.
We saw a different vet for my older lad's annual check-up and he complimented us on his lovely teeth (he'll be 10 years old this year).
We have two days a week where we do claws, teeth and ears, plus a quick groom and that keeps my two clean and smart - but again, it depends on the type of dog and their, er ... habits.