It is not the default behavior in Dorico to have items overlapping. This cannot happen unless you manually tweak the casting off (by inserting frame or system breaks, for instance). You should notice that, deleting all these breaks, Dorico will cast off your music accordingly to the very precise rules it has inside, and you can change some of those rules changing the layout options (cmd or ctrl shift L) — for instance the space between staves or systems. Since you don’t have red nodes (in Engrave mode, with staff spacing enabled) you won’t have to reset those.
I think the right workflow with Dorico (as with any document editor actually) is to input your music, and once it is done, you deal with the engraving part. And you start with choosing your paper size, the margins, then the staff size, then the minimal space between systems…
Once this is all done, if you find you still need to move things around, then you can use system breaks and frame breaks. And if it still is not exactly what you want, then you move staves with the right option enabled in Engrave mode. And you can also tweak the note spacing if needed.
As Daniel explained in an interview (I think it was for Clarineet, in december), the Dorico devs have been inspired by Adobe’s Lightroom, where the workflow is clearly explained in the design of the app : start to work on you pictures with the functions on the top of the list, and go down the list following your needs.
