How to Design a Campaign for Semi Weekly Two Hour Sessions without Just being a Simple Dungeon Crawl?

I am so used to structuring a game for 4-5 hour weekly sessions that I am surprised at the problems with my current group who for "reasons" is currently meeting every other week for 2 hours.

Session Design

I didn't realize how subconsciously ingrained my session design pattern was. I seem to have instincts for a 4 hour session. The session has a beginning, middle and end. The best sessions, start with a recap that transitions into a middle that has some variety (combat, exploration, social) and end on a "button", a fun moment or a teaser for the next session.

With a 2 hour session, there is time getting started, then time doing the recap (because it has been 2 weeks this becomes mandatory). Unfortunately, this beginning time is cumulatively more of the campaign because it happens many more times. I call this "session compression".

But the real challenge is the middle, it is very hard to design the middle. For example, I created an encounter that was basically 2 small rooms. There were opportunities for 3 conversations, none necessary, but my party likes to talk to NPCs. There is a threat and a probable battle with the 3rd NPC.

It took 3 sessions… about 6 hours. Given the overhead of the "beginning", that feels about right, that it was about 4-5 hours. But because of the short sessions, that wasn't a single night, that was a month and a half of real-world time. On the surface, maybe it doesn't seem like a problem. However, this simple encounter now seems like a major part of the overall campaign… when really it wasn't intended to be that. And, strangely, even though the NPC conversations may have taken the same amount of wall clock time, the fact that it took a whole session (or more) seems to make it feel like we are moving at a really slow pace.

Lastly, it is much harder to "end on a button" because it is harder to plan exactly where you might be in advance, and more often, you are in the middle of something that isn't done yet and needs to be continued.

Campaign Design

My normal style of campaign is to have intrigue and NPCs with plans. This allows me to react to the players' choices and make it more dynamic and feel like less of a "railroad". However, I have found that due to the session compression, having a reliance on NPC interaction can be a problem. In the above example, even in a "roleplay heavy" group, it can unexpectedly turn into 4 weeks of social interactions. There is a feeling that we just have to move on, even if it isn't organic.. Whereas in a 4-5 hour session, there might have been a battle in the middle to mix things up.

The result is that I am trying to figure out a way to make it very flexible, so that he party can go into and out of social and combat situations by their own decisions and not because of a limitation of the Campaign. For example, it is easier to do this in Dungeon of the Mad Mage because the party can run up to Waterdeep when they want to and run down to the dungeon whenever they want (for the most part).

TLDR; Summary

So, any advice or techniques for shorter sessions to keep things feeling crisp and dynamic while still having a fair share of social, combat and exploration?

Note: before anyone says "talk to your players" I already have started and intend to continue. I am just gathering some advice so that I can talk to them with maybe some ideas of how to change things and see what people think.