its all about intensity bro if you only have a hour than you have to up the intensity short rest intervals like 60 seconds at most and put everything you got into your sets. when i know that i only have a limited time in the gym i stick to the basics will give you my arm routine i did today and my arms are hurting and it only took a hour
i like to start with biceps first

barbell cheat curls 3 sets 8-12 last set i go to heavy and i cheat the weight up but on the negitive i controll it and let it down real slow

preacher curls ez curl bar close grip 3 sets 8-12 reps

rope hammer curls 3 sets 8-12 reps

seated incline dumbell curls 3 sets 8-12 reps

so on the third set of every exercise i go to true failure and if you have a training partner you can get him to help you lift the weight up when you got nothing left and do controlled negitives

triceps

close grip bench 3 sets 8-12 reps

skull crushers 3 sets 8-12 reps

dips 3 sets 8-12 reps

cable pushdowns 3 sets 8-12 reps i like using the easy curl cable bar but the rope is fine to

single underhand cable pulldowns 2 sets 8-12 reps

so that was my arm routine today and like i said a hour to complete, i only rested 60 seconds at most between sets and every last set on each exercise was done to true failure,also dont forget to controll the negative part of every move its just as important as the positive