My tractor is nearly identical, so here is my experience (my property is completely flat basically, so that plays a factor).
General driving around the property with or without a load is typically in 5th or 6th gear (some loads will require low though). My ground gets a little too rough to run in 7th gear. Ive only ran it on the road in 8th gear once and that was for about 10 minutes. Also when using the loader to say go into a dirt/gravel/mulch pile I will run into it in high gear and push clutch in once it hits the pile. If needed I will then shift to low and continue in to fill the bucket.
For mowing it all depends, I use anywhere from 3rd-6th gear depending on conditions.
Pulling disk harrow is generally done in 4th-6th gear, again depending on conditions.
Running the tiller, 1st gear.
Box blade work, 2nd-3rd gear.
I will also note that I hardly ever run the tractor at PTO speed (except mowing and tilling obviously). For uses besides that I typically run between 1500-1800 rpm, match the gear to the task that keeps it in that range.
My biggest annoyance with the ranges though is the low/high and reverse range ratios. I wish they would have matched the reverse ratio to either the high or low range ratio. Reverse seems to be a medium range and at times when doing a lot of forward to reverse changes it gets annoying. And yes I realize a gear drive is not ideal for this work, but I had no choice in transmission type when I got my tractor
Next one will be a HST tractor (but the 3200 will stick around too
)
Only advise I can give to you questioning if you should use high range or not is to just ride around without a load or doing anywork and see if you feel comfortable with it.