AFAIK no, as even minor updates could lead to problems (and that's the whole point of the Extras QA process). It's only ten days, which is not too long, and you can do instant promotions from Extras-Devel to Extras-Testing, of course. Also, PR1.2's Application Manager allows single .debs to be installed from the file manager, so you can instruct your users to download only the updated .deb from Extras-Testing (without even enabling the repository) in the mean time (again, only one week and three days).

You can tell your users to vote for the package in Extras-Testing after testing the package, so you get your 10 thumbs up in the 10 days and can promote right after that. Another helpful hint is to promote packages you want to get into Extras very early to Extras-Testing, as the 10 days start to count from the time the package is put into Extras-Testing.