The more I shoot, the less gear I use. I started out with a 50, but this quickly evolved in to a 21/35/50/90/135 combo on multiple bodies, with all sort of other junk.
The gear trap can be difficult to escape. I tended to take along a lot of gear, so I would be prepared for everything I could possibly encounter. After a while I noticed that no matter how much gear I took along, 99% of my shots were made with the 35 / 50 combo and one M body. Everything else was dead weight that was slowing me down and distracting me, because with that much gear I constantly had the wrong lens mounted, the wrong wrong camera type in hand or was shooting the wrong format for the situation at hand. Turns out this was mostly psychosomatic. So, eventually I let go of the security blanket and put everything, but two lenses and bodies on the shelf.
Also, over time your eye (hopefully) evolves and your lens choice corresponds to the way you see the world. (very difficult to get to this point with a zoom...)
So, now I'm down to the 35 and 50. I carry two M bodies, both for redundancy in case of failure and so I don't have to juggle lenses. I also like to put Tri-X in one and Delta3200 in the other, for day and night shooting. If I am going on a real shoot, I'll also toss in a Rolleiflex 2.8/80 or Nikon F/F3P, because I really prefer to shoot a 50 on an SLR for framing accuracy.
And it really works. My shooting has improved and I now 'see' like a 35 or 50.
You look at the work of most great photographers and you will notice that the vast majority of them eventually settled on one or two focal lengths. (Capa 50, HCB 50, Winogrand 28 etc). There are exceptions like Eugene Smith, who apparently used enough gear to stage the invasion of a small country, but then again it does help if you are a 'slightly off kilter' genius...
Last spring at the VII Photo Seminar Christopher Morris told us that he only carries a full frame Canon and the 2.8/24-70mm. If I remember correctly he may also have a fast 50, but borrows a 80-200 zoom for the occasional shot from a fellow shooter.