it is important to wait 1-2 minutes between sets because you must have enought energy to do a set of repetitions .... if you dont you will have bad technique... you can injure yourself and you wont get best results.
you need to rest in between sets for a proper time so you have the energy needed to do your next set .... u may think u have the energy ... and u may be able to complete a set right after another set .... but this is just slowing you down and not giving you any benefit.
you must let your muscles recuperate in between sets.
personally, i like having a good 1 1/2 - 2minute rest in between sets because it lets me do the next set with still almost failing near the end but having enough energy for it to be fun and not reaching pure exhaustion.
hope that helps a bit.
