Our second dish, a small one was for Sky analogue. That was then removed and replaced by a digital one, which he fixed in the same location. Unfortunately it didn't receive very well, because it had to see the sat through the house eaves, so I moved it to the rear of the house, to test it, then (lacking a meter) invited them back to make a proper job of it. This was quite few years ago.
I bought a fancy freesat kit last year, running on the old Sky digi dish and quite soon noticed it was a bit dodgy on some of the channels, but waited for one of those 'roundtuits' moments to check things out.
The roundtuit moment occurred yesterday, when I got out my dish alignment meter. This dish was fitted on an arm to give the horizontal alignment and the arm was back just as far as it would possibly go. My meter indicated it needed to go back a few degrees more, so the only way to get that was to take of the dish and swing the arm to the opposite end of its adjustment (180 degrees) and refit the dish on what had been the rear of the arm. The vertical alignment, wasn't far out.
I now get much more reliable reception of some of the less powerful channels on Astra. The moral being to not assume that they have bothered to do anymore than align the dish to be good enough to get the basic high power Sky channels.
The best time to check it is when there is a good clear blue sky, when it will be much easier to get a steady signal - but Sky installers obviously don't have time to wait for this.