I like to have about one or two combats per session, while in another campaign; my DM only really does boss encounters right before we level up.

My party has quite a few tools to resolve encounters without whipping out the initiative tracker, and fights are pretty much only inevitable in the optional dungeons, so it averages out at 0.4 combats per session.

Varies wildly depending on system, but I generally try to make sure there’s some sort of large conflict that they’re trying to solve which usually has a few smaller conflicts involved. In DnD those smaller conflicts are often combat, but in Forged in the Dark games there’s more variety.

It’s rare that the big thing for a session is combat unless I’ve set up some sort of boss battle, but hey, sometimes the players want to kill things, I’m not gonna stop them 🤷

I vaguely aim for 1 combat encounter and one social or puzzle per session, but it mostly comes down to what the players decide to do.

Depends on the system. Classical fantasy adventuring? Most if not all sessions. Adventure and Sword&Sorcery? Sometimes, half perhaps. Character drama? Very seldom.

I look at how the system spends its page budget and use that as a guideline. If there is a chapter for combat, one for harm and recovery and one for combat magic then the system wants me to focus on those parts. Also I look at how the players/characters are rewarded and try to have each session hit several of those criteria. So if the only (reliable, non gm-fiat) way to earn rewards if through combat then you bet your sweet ass there will combats each session.