I can't speak for all of Europe (naturally), but the places I've been it's not very common to get spots like "the seven" etc. You are more likely to get games on the wire in rotation style games, and balls in straight pool and also in one pocket (which is practically NEVER played, except by a few world travellers). I just thought I'd make this clear before I continue.
Anyway, I don't see much of a point in playing with spots of the American nature. First of all it changes the nature of the game itself too much. Playing with the wild 7 or something similar completely changes the game, and it is no longer realistic match practice, neither for the spot giver or the taker.
Second: I you are going to adjust the spot during the matchup, what is the bloody point of it? You are neither practicing properly, nor will it be easy to make money since you will reach an equilibrium point sooner or later especially if you are not allowed to "quit winner". This is especially true when you are playing in your own pool hall. Hustling strangers is another thing all together. Of course this is where the hustling comes in where you grossly misrepresent your skill beforehand to "have a place to go" later. What can I say, I don't really enjoy that hustling stuff..
I never got the "gambling big with your fellow pool hall regulars" bit. Of course every pool hall has a sucker with a gambling problem, but I'm talking about good players playing each other every week. Eventually everyone breaks even, and you're only passing the same bills back and forth, only it's tied up because you can't ever spend it. How f-ing pointless is that?! At one point I remember in my pool hall that actually happened. When all the debt of 6 or 7 players was totalled with complicated passing back and forth of money it all evened out. Nobody owed anybody anything...lol. Might as well play for small change, that way you can keep it and the exitement is still there (to a degree). Or how about playing for the enjoyment of the game...oh, that's right, I forgot: Most of those guys don't really love the game unless something is on the line..Oh well.