It should be possible to generate main parts over several sheets. It can happen that assemblies are so large and complex that you need a lot of sections that do not all fit on one sheet.
It would be great if you could move these sections to another layout.
Otherwise you are forced to generate an main part several times so that you can create all the sections. Unfortunately, this does not result in a proper drawing.
It becomes confusing because, for example, the sections have to be numbered starting from the beginning each time.