Yeah,this is a short hand method of writing.thats y why we use, U for you,dat for that,Y for why,N for And and so on ................
AssalaamuAlaikum WRWB,
You see, my greetings are complete but WRWB means WaRahmatuallhiWaBarakaatuah.
It depends on the scenario. If some wors are very very long then you could shorten them on the basis of their second priority.
BUT, you do not need to shorten every other word that it looks like your mouth is broken (at list the reader feels like that when the words transfer to his mind).
So please do not try to argue what "YOU" think to be right and what "YOU" think should be done. Writing the common words completely is a necessity, otherwise it becomes a disease and once you get addict of that then it becomes very difficult to get rid of it, while all the other people who are not 'abnoraml' in English writing, they keep on feeling disgusted on such language of "Jerky boys"
This language of "dat", "4ever", etc. is the symbol of that modern Jerky culture of the West.
WE MUSLIMS ARE DIFFERENT. Be Muslim, Be better and COMPLETE.
Wassalaam.