How Long Between Bike Purchases?

[oz rider]

... 6 months ago ... hybrid ... thinking of a road bike.

That's standard in my world, hehe. You don't need to justify it; it's mathematically N+1 where N = number of bikes you have and +1 is the number of bikes you need.

Sounds like you have an idea of what you want to do with it, and I would suggest you focus on the bikes that fit and do the job rather than brand,so test riding is good. But also, don't buy for what you want today because most people find they can do so much more than they thought; buy for what you might want to do in 12 months' time.