This may sound silly but after a few home improvement projects involving minor plumbing tasks (like changing faucets) this has always bothered me.
I'm going to talk about the specific example of an angle valve since it's the one I've faced more often, but this could apply to any kind of plumbing accessory that you twist on until its tight.
I've included an image below of the kind of thing I'm talking about in case the translation I googled is off.
In Europe at least, usually you have a shut-off valve like the one in the picture on every water point in the house. In my case, in the house I moved in, I had some very crappy ones with plastic handles that broke with time and didn't serve their purpose anymore (you couldn't use them to shut the water without using pliers)
When installing the replacement it bothered me that I could not get it tight and pointing to the direction more convenient to then connect it to the appliance/faucet.
Logic seems to dictate that it's however the ridges/groves align between the female point on the wall and the valve's male connection but it's weird for an amateur to see that such a detail would be left to luck or expecting that the female point on the wall was mounted with any intention regarding ridges or what will connect to it.
When I faced this, first I tried starting to twist at different points but found that they only engage at very specific points which makes sense and shows the same result (or same 2 results in some cases) no matter where you start. Then I thought just to tighten it to the maximum then go back enough until it's in the position I want it to be, but even when properly using Teflon tape around the grooves I've found that it needs to be absolutely tight to not have any sort of leaks.
Is there any trick to it?