I'm working with my team on developing a web app, and our users are expected to come from across browsers (Chrome, Firefox, etc) / OSs (Windows, Mac, Linux) / devices (Mobile, Tabs, Desktops).
We are now working to define our testing plan, and we feel that trying out each and every combination (e.g. Chrome - iOS - iPhone, then Chrome - iOS - iPad, etc) is going to be overkill. Also reading through: https://stackoverflow.com/questions/9853497/any-difference-between-chrome-on-mac-and-chrome-on-windows? & https://stackoverflow.com/questions/4299799/cross-browser-compatibility-issues ; we get the view that there are sufficient similarities across platforms for there to exist a smaller sub-set of combinations, which should take us to (at least) 90% reliability.
My question is if someone has done this exercise before, and what their conclusion was - i.e. which browser / OS combos did you finalise on? Else, if that is always going to be very specific, what's the best way for us to figure the right set for us?