Muscle experts, effects on muscles

I do light weightlifting at work intermittently, using dumbbells... example 15 biceps curls and 15 triceps extensions ....  then go back to work.  Maybe over the course of eight hours I'll do 4-5 different exercises with 15 reps for each of 3-4 sets.

If I wait up to 2-3 hours between sets, does this defeat the purpose of the resistance training?  Should I try to get all sets done at once for one exercise?  Could someone explain the actual effects on the muscle of waiting versus not waiting between sets?

you should try and get it all down at one time. when you wait you will give your muscles time to recover and/or not create enough stress on your muscles to cause muscle growth. when you do multiple sets at one time you create a larger effort put forth by the muscle, the harder it works the more demanding it will be, the more demanding it is for that muscle the more it will be forced to get bigger and stronger. you will create micro tears in the muscle that once they repair themselves your muscle will be stronger and bigger and firmer

thanka bodyscience, no one has explained it to me that way.  I'll do all the sets of a particular exercise at once... then do the next exercise (and all sets) the next time I'm able to work them in.