I cut out a section of pvc and attached the new section with couplings on either side. I was able to fully seat one side but the other side was much harder.... the coupling end and the pipe were butted very tight. I was able to cut the pipe a tad, prime and glue, and get it into the coupling but it is not fully seated.

Am I setting myself up for failure?

When two pipes or a pipe and fitting are butted like that, with no way to get slack on either side (this case screwed pvc into cast fittings) what would be the best way to get this done?

if you only have 1/4 inch inserted you will be in trouble. if you a good inch inserted you should be fine..
when there is no side to side movement, you use a slip (repair) coupling. it has no stop in the middle so it will slide all the way over the pipe and then back to the proper depth seating.

How do you apply glue to a slip coupling? Makes a real mess I suppose.

quote; How do you apply glue to a slip coupling?

Very, very, very quickly, and hope you can slide it into place before it grabs and sets.

Whats the trick to it?

Do you apply primer and glue to coupling or to the pipes?

apply to both.

To Everything, but you have to be prepared properly so you can slide it back line up the pipes then slide it into position in a matter of seconds. Almost impossible to do unless it is a very small pipe.

A banded fernco coupling is probably the better alternative then I suppose?

The way the terms are usually used, "Fernco" and "banded coupling" are two different items.

OK my bad... so is a fernco or a banded coupling better than the repair coupling in this case?

If this a drain pipe(original post didn't state), I think the shielded coupling is better than trying to get the slip coupling in place. If a pressure pipe, you need to use the slip coupling.

quote; If a pressure pipe, you need to use the slip coupling.

I would use a union for a pressure pipe.

Its a 1 1/2" drain on a lateral.