So, it's been a number of years since I built a full web site. Most of the time, I'll construct a home page and secondary page, then that's passed off to a client's developer to flesh out anything more. Or I simply build one-pages/emails that are tested for basic mobile sizes but not everything.

I'm refreshing my own site and am coming to realize the breadth and scope of possibilities in today's web pages - Desktop, tablets, mobile.. portrait, landscape. Ugh!

That could be a least 10 different scenarios any single web page could be viewed through. Then factor browsers/OS and that 10 gets multiplied for each browser or separate OS which needs testing. I realize that most testing won't show any necessary alterations for all screen sizes.

I'm aware of media queries and how to utilize them to create dynamic content shifting/changes as necessary.

What I'm curious about is what are professional web designers testing in 2022?

Are the 5 main viewport sizes - 1440, 1024, 768, 425, 320 - all tested in both portrait and landscape?

Are most popular browsers tested - IE, Chrome, Safari, Firefox?

Essentially, from a design standpoint...

Is there a systematic approach which assists in all the testing which may be necessary?

Note, I'm not referring to markup or development. Obviously, if testing a design, at a minimum CSS and HTML need to be considered. But I'm not seeking any markup assistance. Rather I'm more curious about any helpful procedures others may have in place.