Re: Odd or even number rods?
If I were starting over again, say a fire destroyed all my rods, I would stick with odds or evens. Likely with odds, as I think the 5 wt is the foundation rod that can used for most species of freshwater fish, except the pike and carp family. A 3 wt is a good step down and when fished with a 4 wt line, you get the best of both worlds. Going up is a bit of toss up, but if bass is on the menu, then the 7 makes sense.
Ok back to reality, what I have are 2-4 wts, 2-5 wts, 2-6 wts, and 4 spey/switch rods. 90% of the time I pick between the 4s and 5s based on the fly i'm fishing. Tricos and small olives have me reaching for the 4 wts. Hendriksons and similar sized flies draw the fives. Big drakes and hex bring out the sixes. Double nymph rigs with indicators get either the 9'6" six wt or one of the switches.