I hunt in Kansas and in the western states and AK. I use Leica 10x42 Geovid HD-B binos, Swaro 15x56 SLC binos, and a Kowa 554 compact spotting scope. I only rifle hunt and that affects my choices.
What I've found works for me is this:
Kansas I like the spotter for scouting. I use the 15x binos most of the time, but like to dial up a buck with the spotter once I find one worth really checking out. I use it to see how old I think a buck is and look for features I can use to identify a older buck when I'm hunting him. At last light it can keep me from making a mistake on the wrong buck. Hunting I don't usually take the spotter, just the 10x in a chest harness and the 15x on my tripod.
Elk or antelope I just take the 10x42's and spotter. They aren't hard to spot compared to deer with 10x binos, the spotter lets me judge them. Where I elk hunt it's late season and a lot of bulls have broken points and are in really nasty places. I want to be able to see how broke up one is before making a long hike in to get him. I use the 10x on the tripod a lot hunting elk especially.
For muleys I spend most of my time running the 15x binos off the tripod. Scouting I always take all 3 optics, hunting always both binos and sometimes the spotter. I can tell if a buck is one I am interested in pursuing to at least a mile with the 15x binos on a tripod. I'm usually not after a certain score, just a big framed mature buck. If I draw a tag where I can be more picky, I'll take the spotter. Big muleys are to hard to come by where and when I hunt to be to picky, the binos have told me what I need to know for the most part. When I have packed the spotter hunting I seldom seem to use it, I'm often hunting tighter country where bucks feel safe, and just can't see far enough to need the spotter. The bigger stable field of view of the 15's on a tripod lets me see movement better than anything else I've tried, and that's how I spot a lot of my deer.
Anyway, long answer but it should give you some information on how I use each piece of glass, maybe make it easier to decide what if anything you want to add.