Tbh, for drabbles and little things I tend not to bother with betas either, but for me it's an absolute must when it comes to long, srs bsns fic. I think in general I'm pretty good with SpaG, but there's always the chance that I wouldn't catch my own mistakes simply b/c I'm too familiar with my own work.

Also, I'd be happy to beta for you if you ever need it :)