When it comes to training in boxing, is throwing the same type of punch repetitively a good way to develop punching power and speed? An example would be standing in front of a mirror and doing a hundred jabs, then maybe a hundred 1-2s (jab-cross) etc. I realize this would not be good ALL the time, as I know there is a lot more to boxing than just standing still and being able to throw good punches. But for a newbie needing to develop punching power as well as technique (not to mention better handspeed), would this be a good thing to do to start off with vs. just randomly throwing punches while shadowboxing? I would think so to help muscle memory and whatnot, but I figured I should ask some people who have a lot of experience with this.
Also, would it be good to do repetition boxing on the heavybag?

(I have no boxing experience whatsoever and I do not have access to a boxing gym at this time).