The 2.4 operating systems problem: a case study in special pleading

I'm wondering whether this is something I should have read about somewhere. Answers please. The condition is this: a *NIX comes along. Let's call it system A. I learn enough to potter around in it. I make some changes, and start to remember where the config files live.

Then along comes another *IX, or perhaps an *UX. An*X, anyhow.

And I start learning how to use it. I build up a small but valuable knowledge bank that is almost wholly composed of exceptions: all the daemons are started the same way as system A, except the path is different. All the terminology is the same but the file structure is different. So far, so good.

And then comes another *X. Why? well, something to do with work; perhaps fashion; perhaps a new hardware platform. Marvellous. Except that there is now have a three-way set of exceptions. Experience suggests I can cope with two; I can't cope with three. [At the last count, of the six *IX and *UXes and brethren that I'd come across, three were self-imposed and three work-imposed (with one of those overlapping).]

None of this is radical or new. I'm just wondering if, by labelling the thing, I can remind those *X pioneers just how much trouble it is to correctly file and recall those subtle exceptions. That's all.