This is as simple as it gets. - YouTube
If you buy one of the larger template kits from marketplace you can see how people are using them.
But in order to learn you need to break down someone elses project in order to see how it completely works.
A great montage example that I can think of is any game where you pick up materials. Think Tombraider. Your inputs are disabled for the moment you find a material until the montage finished. Some fighting games use them as sequence bits. Punches, kicks, recoil, and reload. etc. Because the dont want you to punch, and kick at the same time.
Your not using the entire state machine to fire off those animations. If you were using state machine. it would be more complex. If you play darksouls you know the montage for taking health.
So if I wanted to just kick an enemy, or give a player a simple animation sequence use montage. I wouldn’t use montage for something like say swimming. Where you want the character to swim up, down, forward, and back. You can make your own slots, and notifies. It’s a long process of learning all of that. Couch knights uses a simple slot, and notify with montage. It’s free.
marcin published 2 kits that I know have tons of gameplay examples. Side Scroller Shooter Kit - Unreal Engine Marketplace - Trailer - YouTube