For some house, ang studs ay nasa mga 18" - 24" apart,
which make some wall mounting ideal (not all), newer houses are different...
like what happened to my house, when Best Buy was gonna wall mount my 75" sa bedroom,
we found out na magkalayo ang stud dito sa master's bedroom, kaya hindi ko magagamit ang wall mount
na nauna ko ng binili, the tech guy was suggesting installing a 2x4 at the back, meaning, yung muna ang ikakabit sa
magkalayong stud, it will work, but the fact na medyo pangit sa isipan ko, and magpipintura pa ako sa likod, I declined,
we ended up buying a new one, the higher model one na may malakaing adjuster sa pwedeng igalaw at umabot sa
studs. Using the plywood is basically the same thing, yun ang ikakabit muna sa stud, then sa plywood nila ilalagay ang wall mount.
Pictures via Google... Hope this helps,...