the 'professionals' find a setup that suits their style! This is a thing you get to learn by doing more.
Basically the way I came up with my combination was by learning for a few years on a Selmer C* mouthpiece. Only when you find that with repeated performances you still can't get the sound you're trying to achieve should you really start changing mouthpieces, since your embouchure won't ever settle if you keep swapping pieces.
When I decided to leave classical playing behind I found myself a metal Otto Link and learned to play on that. A couple of years later I decided that the lay wasn't wide enough and then bought a bigger one.
As for reeds, they're not like a grading system for your standard - once you've found a combination of sax and mouthpiece that sounds good with your embouchure, then work out if any other reeds sound better on that combination - at the low and high extremes of the sax as well as in the middle. Standard (cheap) Rico reeds work really well with the Links, though I use La Voz MH since I find they're more consistent and I can usually use 9 out of ten straight out of the box.
If you want proof of this, check out "Doc" Kupka (Tower of Power's bari player) - wide lay, really soft reed.
I notice on Theo Wanne's site that Cannonball Adderley played La Voz M reeds - and listen to the sound he got!!