it helps everyone, when people fill in the blanks about themselves, even things like where you are from can determine riding habits, types of fuel, roads, climate, local shops, regionally sourced parts
the only thing I hate is chain drag, or belt slap in our cases, scares my internal visual on what may be happening to the crank, belt or gears, I have a 7 year warranty, would rather not use it, I'm sure it's not the right phrasing, but lugging out below 2600 rpms, generally has me upshifting.
but I motor boat frequently now, (cruise at 2k, or visualize pam anderson) but to break everything in, tried to keep the RPM's up for the first 12k mi. above the 3k.
I like the way my bike does at 3500, usually keep it around 3k.
You can get good mileage in any gear, it's more of an RPM and drag coeficient issue, finding your bikes path of least resistance, within legal limits of course.
For that matter, these newer 6 speeds still get great mileage at 90+ all day.