Sometimes even the best box joint cutting will still produce a slight problem when glue is applied. I always use parallel clamps to pull the joints together, but sometimes I still get an area where part of the corner is too tight and the clamps aren't pulling it completely together. For these, I found that hitting the end of the clamp nearest the failing joint with my dead blow hammer has added just enough additional shock pressure to get the joint to go together. Once together I always check the diagonal measurements to be certain that the box is square, and I'm now in the habit of doing this several times before the glue completely dries.
Using parallel clamps to force the joints together can bow the box sides, so I always let the glue set up for about an hour after I've made certain that all the joints are completely together. Then I loosen each clamp to allow the box sides to straighten to eliminate the bowing, but still leave the clamps in place. The glue is still weak enough that the sides will straighten, but the clamps will hold just enough pressure to keep the joints from opening up. Several hours later I'll remove the clamps and set the glued assembly carefully somewhere for it to dry overnight before I do any additional work on it. When assembling many boxes, I sometimes end up stacking these glued assemblies, rotating each 45 or 90 degrees from the one below it, because I can run out of bench space in my small shop very quickly. The unused area of my Unisaw side and out feed tables, covered with a piece of Kraft paper, is where these glued up assemblies usually get placed for the overnight drying time.
When I bought my Unisaw, it came with a 52" Unifence and even though my shop is very small, I couldn't bear to cut the fence rail down (I'm hoping to some day have a larger shop again). So the right end of my saw table is up against one shop wall between my garage and passage doors, and my work path is only around the left end of the saw.
Titebond Extend glue is almost a "Must Have" when gluing box joints. It takes time to put glue on all of the needed surfaces and assemble the box joints. Unless the box is very small, the regular Titebond glues just set up too quickly for this type of extended assembly process. The Titebond Extend makes gluing up box joints much less of a race condition. A tip - put blue tape next to each joint on the inside ends of each box side to make it easier to remove the glue squeeze-out later. Squeeze-out on the outside of the box can be sanded or wiped off easily. Not so on the inside of the box. I carefully remove the tape after I remove the clamps, but while the glue is still a bit soft. If you wait until the next day you will need a scraper or chisel to get the inside of the joint completely clean of glue squeeze-out. It will almost always peel off easily on the tape if you remove the tape about 2 hours after gluing and assembling the joints.
Central North Carolina