I know where you are coming from
@klaus,
When I go to see a new client about designing a new business app for them, I always ask them if they have any thoughts about the basic look and feel of their bespoke app. Somebody in the meeting inevitably pulls out a phone or tablet and shows me an google designed app, usually Gmail or Google news, but never ever FB for some reason, what are they hiding lol. Sometimes they show me other apps but the general design principal is basically always the same, some variant of Material Design.
So my thought is a simple one. I've basically pre-made all the most common variants that I've made for my clients, that saves me time when starting a new project. As I only make business apps, usually warehouse management systems, invoicing/epos solutions, stock control, taxi fees, mobile courier solution etc etc etc. With a few simple changes for functionally and obviously screen design and layout, I find that business clients usually want one of four basic designs and that's simply because lots of downloadable apps on the play store use Material Design and clients like that, but not always.
Obvious I come across clients that have a completely different design in mind, then I have to create everything from scratch and either create myself or try to find libraries or classes to suite.
But I do find myself using my templates more often than not, and that's not by my choice, but the choice of what my clients say when I ask them their thoughts. I really do enjoy putting together everything from start to finish, but if a client says that they want the look and feel of GMail, Play Store, Photos etc with some minor changes like toolbar and drawer menu etc, I already have it ready to hand and I even have multiple color themes ready, about 20 in total. I don't create bespoke apps for clients that want to put the app on the Play Store, that's too much hassle and there's way too much that can go wrong.
I do create apps for clients that look totally different with what I call strange designs as in look and feel, but if that is what the clients want, then that's what the clients will get, they pay the bill after all.
Nah, you're still young at heart Klaus...