Having owned both brand new and 10+ years older basses, I can tell you this: In MOST cases, new basses (with their 'new' wood) are going to move around action wise unless you're very careful to replace the old strings with the SAME set. Even builders who are careful about moisture content and storing the wood for a time before building/milling, as ALEMBIC is, can not control the finished piece completely: Like Mica says, sometimes it takes a while before the wood realizes it's no longer a tree. Over several years, the wood ultimately stabilizes with the finish in terms of sap, moisture, finish, glue, etc. My older basses are a breeze to adjust as all that aging is finished.
Going to a different set of strings every time is just asking for the the neck to walk around on you. If you don't mind adjusting the action for each new set, go for it. It often takes several new sets/brands to find that perfect set for a new axe. But you will be multiplying your aggravation chasing a perfect setup for Brand X, then have to start all over with the very next set of something completely different. You've discovered that each different set presents the neck with an entirely different set of pull.
My first advice is to find one set that does it for you and stay with it as soon as you can. And remember that truss rod adjustments rarely show themselves 100% at the time you do them: It may feel fine today, finish moving over the next few days, and ultimately end up not being what you wanted. With new axes, I do it in baby steps and try to work up to where I want to avoid big changes that don't settle in for a few days: It only tends to confuse me and I wind up going in circles, seeming to go past it, than under it, then past it . . . . you get the idea.
I sometimes find the best thing is to play something else for a few days, then come back when my mind is clear again!
J o e y