I would recommend the OT as master.
Then if you wish you can use song mode or even more banks and patterns.
I have a couple Template projects I load up, and save to new.
At first I’l just kind of make various patterns in different banks, sketch out ideas, etc.
Over time some of these become longer songs, or a group of tracks that go together.
Some projects just sit around, get thrown away, or revived.
Over time I’ll want to consolidate projects (songs) into one new one, creating finished material, or a live set.
It can be very tedious, but it kind of just depends on what I’ve done in the separate projects so far.
Basically I’ll sit there, and open the projects I want to grab a song from, use copy and paste functions to grab kits, parts, patterns, open the new project and paste them.
You can only copy one thing at a time, so it’s a lot of back and fourth, checking things, re-doing things.
A lot of times I will grab just a minimal amount of patterns in a bank from some sketched up song, rework it a bit in the new project.
Sometimes I use OctaEdit for the OT.
You can also put the OT into USB Disk Mode, and copy/paste +rename files.
I’ve tried these ways, but I kind of prefer the tedious way.
It offers a lot of other things you might not think about.
For one, you’ll learn the project like the back of your hand.
It makes for great muscle memory.
You’ll memorize parts of each machine.
You’ll start thinking of different ways to do things with random patterns in various projects.