Advice about players spending too long planning for encounters during the game?

I am a lucky DM. My play group is steady, we are all passionate about our game, and the players always try hard to play well because they care a lot about our homebrewed world and its people. A big part of this campaign has been that my players really like to slow down before big encounters and talk through what we should do to prepare for it as a group. We know that we play slow and it has even become an inside joke at our table. I used to take it as a compliment because I thought it meant that the players cared so much about the adventure and characters that they believed it was (fictionally) real and therefore really wanted to do their best.

However, over the past couple of months, this habit has ballooned out of control. Entire sessions have been hijacked by this beast, and they are slowing down to a standstill before every encounter. Some players are starting to get frustrated and want to just move on while others then feel hamstrung when they still aren't finished discussing, debating, and planning, even after 45 minutes, an hour, 1.5 hours... I don't like cutting them off because I can tell they are passionate about playing well and that this is part of the fun. But it's getting to be too much. And now that it's breeding bad vibes, I need to step in and address things.

How do you guys approach this, or how would you? I know the players well enough as people that they are very open to compromise and we are all good friends. Set a timer? Elect a shot-caller? Announce 5 more minutes and then call for a vote?