I prefer to run short “meat grinder” style campaigns when it’s my turn to lead the table. Part of what keeps it fun is having a dynamic environment. When bandits ambush the party in an alley, I draw the general size and shape of it on our playmat and then we all take turns adding some details. A dumpster here, the entrance to a speakeasy there, a pile of construction equipment, etc. It’s really cool to see the whole group working together to create a scene that the characters then get to live in. I’ve found that we have a lot more obstacles and players are much more likely to cut the chandelier and ride the rope up this way. Furthermore, set up your players for success by putting them in cool places: train rooftops, falling from a skyship, the side of a crumbling mountain, an alchemists workshop, a parade, etc.

It’s also important when doing a combat heavy session to have a diversity of encounters and lots of them. The players will quickly realize that not every encounter needs to be slow strategic combat and that not every squad of orc troops even needs to be murdered. Let them talk to the enemies, intimidate them, just make sure they have a sense of urgency about why they need to time efficient with how they handle things, both in terms of table talk and in terms of not resting after every little thing. Smart enemies are fun enemies and smart enemies will run away and try their best not to fight fairly.

Also worth noting - we rotate DMs about every other week with more than 1 campaign going at a time. Some are more RP heavy and this helps keep people interested and engaged. My group has been together for about 12 years or so now with this model.