I have three accounts and five computers and I don't find the once-a-month 6-digit number to be a big deal. PayPal does annoy me with their policy of requring an OTP seemingly every time you visit a page, but it's worth it because I know that I don't have to have a super-amazing password to stay safe. Ultimately, the work required to recover from a compromised account is much higher than it is to type a 6-digit number every month, so I consider it a good trade-off.
In my case, the number always seems to expire when my token is far away. So another way of alleviating this would be to have a three day grace period where you're prompted with the option of refreshing your credentials, but you don't have to.
I'm thinking more like, I wake up and want to check my mail from bed, but -- surprise! -- it's expiration day, and my OTP token is downstairs. And using a single recovery code immeditalely invalidates your electronic token, logging you out everywhere and forcing you to go through the activation process all over again before you can log back in.
