I think it is a pretty good strategy. I'm not sure how much it is protecting turf versus the chickens don't like change and they are more nervous in a strange place, so they are likely to be less aggressive. I'd still suggest having different feeding and watering stations around to help avoid points of conflict. And the more room you can provide, the better.
When you merge flocks like this, you have two separate issues, integration and pecking order. Integration is where the other chickens stop seeing the newcomers as threats to the flock and start accepting them as members of their own flock. Sometimes this integration goes so well you wonder what all the fuss and worry was about and sometimes it results in dead chickens. No two flocks are the same. I do think the more room you give them, the better your odds of it not being too stressful. If a broody raises chicks with a flock and weans them at 4 weeks old, they are already integrated with the flock but pecking order issues are not settled.
Pecking order is social rank within the flock. Mature always outranks immature, but I've seen 15 week olds that have been accepted as mature and are able to dominate grown chickens. I've also seen older chickens still be quite immature. Each chicken and each flock has its own personality.
I've never been a huge fan of the add them at night strategy. I know some people are convinced it is the way to go and it does often seem to work. Some people have disasters when they try it. It may help some on the integration side. I honestly don't know. You still have the pecking order issues. I'm just uncomfortable with the thought that these strange chickens that may have integratin issues and will have pecking order issues waking up together in a fairly tight space where the weaker cannot get away from the stronger if the stronger are really aggressive about it. I prefer them to meet where the weaker can run away. As I mentioned, sometimes this whole process goes pretty smoothly, mainly I think because of the personality of the individual chickens involved. I also think that one of the possible advantages of the add them at night strategy is that the humans are not around when the chickens wake up so many of the integration/pecking order issues are resolved before the human intervenes. But this is only with the ones that were going to be fairly peaceful to start with.
Hope this helps a bit. Good luck!