Hopefully this is helpful -- I was going to get Hughesnet at my shop, but their website's Service Locator map showed my address to be the single black spot in the area (seriously, the next-door neighbor has service and I don't). I went with ViaSat and get good coverage, but had an outage earlier this year. A tech spent half the afternoon at my place diagnosing and then clearing some tree branches for me.
I would have estimated the obstruction to be somewhere around 5-10%. The amount of foliage didn't even look like "shade" to me, but it was enough blockage to prevent the modem from connecting at all.
The tech had some kind of app or gizmo that he placed on the dish that beeped to indicate signal strength. He spent a good half an hour taking down branches before it made a sound, then it was like Morse code. At that point I had a clear view of the sky from the dish and thought he was done. Another 30 or 60 minutes later (seriously, it took a full tank of fuel in the chainsaw) and he finally got a constant, steady tone.
It has been a few wet months since his visit and although I don't use the internet much out there, I think the speed may have dropped a little. I'm probably due for another tree trimming.
He did note that the installer did a really poor job locating the dish. Even though the trees have grown significantly since the install, he said the installer should have seen it coming. Maybe I'll spring to have the dish relocated next year. I hate to treat connectivity better than trees!
I hope to spend some time out there this weekend. I'd be happy to do a speed test and see if Sky Scan can tell me how obstructed my dish is. If it's bad, hopefully I can do some trimming and get a before-and-after.