As have already been said here, size, weight and character make bg differences in what lens decisions to make. I own an older Serenar 28/3.5, that Raid mentioned earlier, as well as the much newer Canon 35/2. The Canon is still a small lens, but the chrome 3.5 is really tiny. There is also a big difference in the character of the lenses. For many scenes, I prefer the 3.5, but the 35/2 is one of my favorite lenses, overall. If I were carrying a Barnack or a bottom load Canon, I would probably put the 3.5 on it, to make a nice, compact package. That's an outfit that works well for street work, and with modern films, it is still versatile.
If I were doing landscapes, I might well go for MF, where weight and size can be compensated by tripod use. I can also have great fun with a MF and a 30/2.8 full frame fisheye. Great fun at places like amusement parks or family outings. The 35mm equivalent is a 16/2.8, and there is a Russian lens that adapts nicely for that. DOF is so wide at that point, that focusing by quesstimate is not a problem.
You will find that as you progress you will either find yourself condensing and focusing on just a small group of lenses, or just the opposite... wanting specific glass to do special tasks,and needing much more equipment. There are also a few people who occupy a middle course, who may be the lucky ones. Anyway it works out will be the right option, if you enjoy what you're doing.
At bottom, fun is where its at....
Harry