When I started fly fishing, I had one very antiquated glass fly rod. I adapted to it. I found enough parts and pieces of old bamboo rods to build what I thought would be an "upgrade." What I ended up with was a 9' 2" 9 weight monster, harder to cast than my glass rod, and not at all suited to dry fly fishing for trout. I then started working in tackle stores, and I could get any and all rods for a nice discount, and I ended up with at least a dozen. Small light rods for small streams, these were 4 weights, then a few different 6 weight rods between 8 and 9 feel. I also had three 8 weights 8.5 to 10 feet for still water and popper fishing. Many of these rods were built from blanks from several different manufactures. Since all I fished for were trout, there wasn't a need for any specific rod when I sometimes fished for panfish, or bass. When I fished in Michigan for Salmon, or PA for Steal-head, I just used my existing 9' 8 weights.
After moving to Florida, I focused on inshore saltwater fishing for larger fish like Red Drum, Snook and Juvenile Tarpon. And I continued to fish my existing 8 weight rods. Never found a rod yet that I couldn't adjust to, and I never found that any rod no matter how expensive made me a better caster. The way to do that is to perfecting proper casting technique. I Still have one rod (a Sage,) that is almost 30 years old, and my newest rods are very inexpensive by today's standards, both under $200. I can cast them as far as I can cast my Sage.
There are rods marketed now for different species, and far too many different types of fishing. I just don't buy into that, why would I want to have a Red Drum rod, A Tarpon rod, and Sea Trout rod, and a Snook rod, when I can (and have,) caught all these fish and a few more on the same rod. i use a 6 weight most of the time, and only switch up to my 8 weight when I think I will be finding fish in excess of 15 to 20 pounds. I have landed lots of trout up to 5# on a 6 weight, and use the same rod for fishing in Saltwater, and use it Bass, and Shad fishing in the winter months. My Sage 8 weight has work for me in Mexico for Bonefish, Permit and Snook, Steal-head, Salmon, Bass, Pickerel, Bowfish, and Trout.
You need a rod that will deliver the fly you want to use, and then be able to "handle" the fish. By that I mean able to bring it to net quickly in good shape and release it will a good chance of full recovery.
Two 9' rods one a 6 and one an 8 will do me nicely.