Do Guardsmen on orders over 31 days report back to civilian work on their next day after rest or up to 14 days after release from orders?

IMLC is 30 days with weekends off if you don't need to retest.
Go to work the next day.
Even if your orders stretch to 31 days.

To elaborate, USERRA is there to make sure you don't get fired for going on periods of active duty. They aren't there to guarantee you won't get fired at all.
If you are in the Guard/Reserve, your Monday-Friday job is what pays the mortgage and bills and is what will pay your retirement. It is in your own best interest to make yourself too valuable to lose in that job.
If you are going to max out the 14 day break every time you pick up 31-35 day orders just because the law says you can if you want to, your employer will start looking for other reasons to let you go.

You have up to 14 days to report back. The "safe travel time and 8 hours rest" is when you are on orders of less than 31 days. From 31 to 180 days you have 14 days. You can always "reapply" or return earlier than the deadlines, in which case the ER must "promptly" reemploy you. This means the next shift for service of 30 days or less, and NO LONGER than two weeks for service of longer than 30 days.

You have up to 14 days to report back. The "safe travel time and 8 hours rest" is when you are on orders of less than 31 days. From 31 to 180 days you have 14 days. You can always "reapply" or return earlier than the deadlines, in which case the ER must "promptly" reemploy you. This means the next shift for service of 30 days or less, and NO LONGER than two weeks for service of longer than 30 days.