I'm thinking about how I'm going to be approaching staging on my future layout, and I like the idea of "serial staging".
I don't. It's not very flexible.
Right now at the club, the mainline west of Sudbury is still under construction, so what is built so far basically becomes serial staging, since it doesn't connect to a staging yard yet. It is double track, so most of the trains can be put on one track (but not all will fit so you need to have some on each track), but you have to make sure everything is lined up in order, and the first ones out must be all on one track and that track needs to be cleared out before anything can arrive from the opposite direction. So you need to plan departures from both ends to make sure that there's a place in serial staging before any new trains to arrive.
Our main construction goal is to extend the line westward and actually get it terminated into a temporary staging yard while we start construction on the permanent staging and then the next phases of mainline expansion. Our main reasons for this being a priority are
1) capacity - using both tracks our staging capacity is currently 4-5 trains depending on length, and that's with 2 trains on the opposite track, so they need to leave before anything can come in. And once that first track is full of inbounds, nothing else can arrive until the last train has left from the second track. There's also some trains on the schedule we're not running, like the
Canadian (which we should have in about a year or so from Rapido trains) and local RDCs, plus some other trains. We need the extra
2) reversing capability. A reverse loop will allow us to turn the passenger train to become the eastbound train later on.
3) extending the mainline for a longer run and adding more towns and locations
Single track serial staging certainly wouldn't work at all, since nothing can come in until everything has gone out.