Back in college my mom saw a couple of my fly rods up against the corner as well as she ask exactly how many of those things did I need. At the time I simply had three, which didn't feel like nearly sufficient, but I didn't inform her that. I just made the observation that golfers do not drive around the golf course with one club sticking out of their bags. For the various circumstances they face on the course, they have a club that best takes care of that situation.
When I first started fly fishing, I purchased a 9 foot 5wt, a common trout rod work steed. I fished it for some time but didn't have as much fun angling for the smaller fish that populated the creeks near my residence. So I acquired a 3 wt. rod. This was the start of the obsession. Much like picking a golf club for the shot, you have you pick a fly pole for the fishing conditions. This made my angling encounter a lot better!