Agree with @Scott F, do what works for you. I have found,
after many years of messing with my kayak rigging that 3
rods - for me - are probably the max I now take. I can get
by really well with 2, and have even fared quite nicely with
only 1.
If you are fishing tournaments, you may need more, but
probably not when it's just for enjoyment.
At least that's how I look at it. No tourneys for me, just out
for the love of the sport. So I tend to fish what works and
not experiment too much these days. Oh, and except for my
casting setups, I have 1 reel per rod. For casting, which I
do not do as much anymore, I pared down to 1 reel and 2
rods....