I've got a similar gripe - the fans don't come on while the card is not under load, but when they do come on, they stay on for far too long once the temp has dropped. When I quit Doom the fans often stay at high speeds until the card core temp reaches the low 20s, which is lower than my normal idle temp, but they still keep going for a long time.
Another quirk I've noticed is when you're idling, you still get a fan speed being reported (600-700rpms in Wattman, 19% in GPU-Z) when they are visibly not moving. I know this is intentional for noise reasons but it sort of suggests that the card is reporting false fan speeds to keep the software happy, which makes me doubt whether I'm ever getting a true fan speed reading.
I'm not entirely sure how much of this is down to drivers more than the card. And despite these quirks I am really happy with the card in every way. It's definitely worth the extra tenner over the Sapphire IMO.