Honestly it varies and there isn't any hard and fast rule. For my SG build, which was a stain and then SCA clear I used 2 cans over about 3 weeks to make sure all the grain was filled.
That's why I mentioned you might want to do another coat of clear after you block back. It becomes easier to see where there are still bit's that need filling once you start sanding.
It does add extra time to the build, but like most things with this hobby, patience is rewarded.