I use 3 very different systems.
http://tgsw.net
I have used TGSW for years. I build a template, upload a few hundred thumbs, set a cron to hit it at 5 after midnight Pacific and that's it.
TGSW is my favorite by far because it works even when I don't.
If you don't know how to set a cron then your server admin can do it. I don't know how many hundreds of thousands, probably millions of gallery hits I've moved with that over time. The beauty is if you upload 450 images then that's enough for 30 days and it'll just repeat OR move on to another category.
There are 67 niches.
I also use Chameleon. This autosubmitter will make all of your thumbs for you AND submit them to the tgps that require that size of thumb.
I also use Russian Submitter. It's pretty good, maybe just OK, and it only submits one thumb size, 88x88 and you need to make it, and it hotlinks it from your server.
Not good if you use hotlink protection, and you better be if you're submitting galleries IMO.
I confirm everything with econfirmpro running on my server. It confirms and deletes by script, subject or sender.
AST