Think of it more as a
perpetual beta. Not in terms of critical errors which might show up (those are very unlikely) but in terms of new parts of the software where the addon will support sprites in the feature.
f.e. the first versions included forumhome, then came forumdisplay and the (never released 0.8 alpha, which was running for quite a while on our live board) included showthread.
Now we are running a 4.1.10 version which does utilize the 4.1.10 hook and are currently adding new icons (forumhome is done afaik). We are not sure yet which name or version number the new release will have. If we switch to the way firefox or chrome do things we might as well name it 4.x