If what you are shooting isn't moving, then one can certainly take many many shots of the same thing, but what is the result? A ton of shots to go through at the end. All of which probably look pretty much exactly the same. Just because you can do something, doesn't mean to you have to. I grew up in the film era when one took way fewer shots because the price of developing and printing film was so expensive. Also, my Honeywell Pentax SLR was fully manual except for a built in light meter, which also slowed things down. I take way more photos now since I've gone digital, but in many ways, I still approach a shot like I'm shooting with film. YMMV, but I'd rather have a few well composed and exposed shots of something and spend the rest of my time just experiencing and taking in the scene or interacting with the friends I'm with, etc. Of course, this all changes if what you are shooting is moving and it's your only opportunity to get the shot.
My point of the above is think about what you will likely be shooting and have an estimate of how many shots you will likely take. (I admit, this can be done more easily for some trips than others.) You may find that you will need far fewer cards and storage than your original post proposes. Also, keep in mind that electrical outlets in European hotels aren't as plentiful as they are in U.S. hotels and can sometimes be, from an American perspective, in odd locations. So, in addition to the various plug adapters you'll need to bring, I'd encourage you to bring some extension cords with multiple outlets into which you can plug all your various devices.