I have to go to school everyday from 8 to 10 MWF and 8 to 12 TTH, and I also work most days 4 to 10. Luckily, my boyfriend works an 8 to 5 shift so Jimi does not spend alot of time at home alone. We kind of worked it out that way on purpose.
When he is alone though, we keep him baby-gated in the back part of the house so he has a couple of rooms but not full-run of the place. He used to be gated in just the bathroom (for potty accident purposes) but over time we just kept giving him more and more space to roam and he hasn't had any accidents at all while we're gone. (I still don't trust him in the kitchen - it is the one place he will still go potty in.. so we are working on letting him have the whole house. )
I used to feel so terrible leaving him alone but I am pretty sure he just sleeps the whole time. When I come home, he kind of has that sleepy-eyed look like he just woke up.
We also have a cat and they keep each other company, because the cat can just jump the gate when he wants to visit Jimi. Toys are also great for when you are gone. There are alot of interactive toys that can keep them busy for long periods of time. (Although these toys do not interest Jimi, he just prefers stuffed animals! haha)
Separation anxiety can be a problem, but if you get them used to you leaving it will help out alot. Even if you just take short trips out just so they can get used to it. Jimi usually whines when I leave, so I always give him a treat and that usually helps alot.
I know you mentioned how alot of people on here go home and check up on their babies during work and such. I think many people do this not because it is entirely necessary (although they might have to potty), but we do it just because we love & miss our babies so much and want to check up on them!
good luck!