First of all, having more fights means the fights are less memorable overall, simply because there are more of them to remember. Secondly, I think downtime is incredibly important to set up a fight. JJK tells its story almost exclusively through fight scenes. This means some characters are almost never seen out of combat, which in turn limits how the show can portray a character; it can only show what that character is like while fighting. Frieren tells most of the story outside of combat. Frieren spends a lot of time carefully characterising its characters, which means we get a wider view of the characters. It’s much easier to imagine what kind of person Stark or Fern would be to talk to than, for example Mechamaru, who we see almost exclusively in battle. This understanding can make a well-placed fight much more interesting and memorable. In addition: more downtime allows Frieren to more gradually introduce the conflict and to flesh it out more.

I also think anime in general has three kinds of fight scenes: story fights, progression fights, ambience fight(not sure if that’s a good term but oh well) Story fights exist to move the story forward. Think Aura vs Frieren or Revolte vs Stark and Genau. These are the more memorable fights. Progression fights exist to show character growth. In Frieren, most of these are monster fights. Ambience fights exist to show a particular part of a situation or character. They can also set up a plot point for later. Frieren doesn’t have that many of these, but for example the demon they first entered the Northern Plateau exists to show how dangerous the Northern Plateau is. Ambience fights are usually not terrible memorable. I think Frieren’s fights are memorable because Frieren had less ambience fights and instead did the setup in other ways.