One thing I notice, and it just might be the way I feel it, but even the same or close to the same gear ratio in the different front rings feel very different to me.

As was said, small chainring for climbing, middle for flat, and large for decent. I am very rarely on any sort of flat when I'm on the roads. When the hills are smaller grade, I can ride them just fine in the middle ring and lower gears on the back, but even if the ratios are the same, if I go to the smaller front and go further up towards the middle of the rear, it just feels a lot different and better.

Same with decending. I don't go into the large ring very often because I don't have much time going downhill before I'm heading up again. I can ride just fine up to around 28-29 mph in the middle and the 11t on the back, but if I change to the large ring and bump it down a few to the 15t, it is approximately the same ratio but it feels completely different and feels better.

This might be all just in my head, I don't know, but for the short amount of time I am going downhill and maybe hit 28 mph, my calculation tells me I'm at 109 rpm while in the large ring and dropped 2 gears to the 15t, my cadence is 108 rpm and though I personally couldn't pedal any sort of distance like that, it's only for a short time and only 1 rpm difference at that speed, but the large ring and 15t feels so much better pedaling than the middle ring and 11t.