Yeah - I was going to highlight the fact that the BBC (and other public service broadcasters running the format) have managed for years without commercial breaks. I'm sure that the BBC Studios team in LA who make the show have UK folk there who can help with the structure.
The BBC durations do vary quite a bit over the course of a season. For example, this year's run (there's only one iteration a year on the BBC) has a one-off 1 hr 50 min show on Friday for the launch, and then the first "regular" show is a massive 2 hrs 25 mins on Saturday. That's in part because in early weeks there are lots of competitors, so shows tend to get a little shorter over the run until they even out a bit. But given it remains a ratings hit in the UK, there's no real incentive to shorten it that much.
BBC One's Saturday night schedules aren't as tightly defined as the average US network. You get sports or other live events bumping things around, and I get the feeling that Strictly is seen as quite an "elastic" show that can stretch or contract as necessary to tidy up timings for the rest of the evening's schedule. They like to hit the news at 10pm with Match of the Day at 22:20-22:30 (I think the BBC has a strict embargo of around 22:25 before they can show EPL highlights).
In terms of re-setting the stage for the next dancers, there's lots of time during the behind-the-scenes pre-recorded segments that run before each dancing partner performs. Add in the post-dance interview "upstairs" from the floor, and there's lots of time for stage crew to reset things for the next dancer.
A couple of other things I'm thinking about with this:
- The technical challenge of live vs pre-recorded for streaming are significant and not widely considered. When Netflix drops a big new season of something, they've had it in advance to transcode into many different formats to suit your internet speed (I've read in the past that there might be 20+ versions). From SD to 4K and everything in-between. They can then distribute those to their "Open Connect" partners globally. So when you request an episode of Stranger Things, it's been transcoded already to meet your internet speed, and the file might be being served from your local ISP in a nearby city. The result is super-fast response times and things play really quickly. On the other hand, with live programming, everything has to be transcoded on the fly, and there's not the opportunity to deliver those transcoded files in advance to lots of local partners within their CDN. So even with the same internet connection, buffering is much likelier. Disney has experience of this with ESPN+, and so will be utilising those learnings on something like DWTS.
- Disney is due to launch an ad-tier soon. With pre-recorded shows that's easier to manage. But how do you maintain ad-free and with-ads versions of something like DWTS? I guess they could put with-ads viewers into delay, although they might be substantially behind "live" by the end of a long show.