Conditioning is always going to be a huge part of training. The mitt work as well. While you may not be learning new techniques everytime, you still need to be drilling the same combinations over and over and over again to build the muscle memory. So just because you know the technique doesn't mean it is going to be sharp when applying it.
As for it being weird holding pads, that is something you just learn by doing. You just have to get used to it and it can sometimes be confusing when holding for a southpaw if you normally hold for orthodox fighters. But I would really try and get comfortable because if you are taking turns holding for a more advanced person, it can kill their training session if they have to constantly stop and go so you can readjust.