Was on a cooking site/forum recently and lots of very accomplished cooks (well, by the sound of their recipes/dishes they know what they're doing in the kitchen,) said their favourite cheat was having a bag of mashed potato in the freezer.
I tried it a few years ago - and I have to say I very rarely mash my own potatoes these days!
Like others, I hate sloppy, creamed mash, like a sort of fondant potato. Ugh. Frozen mash, however, has body and tastes as good as anything I can make. You can jazz it up with butter, pepper, cream or spring onions, to taste, too but it's great as it is.
My most used kitchen gadget is my stick blender with whisk attachment.