[onlinehandyman]

It depends what the job is. The quality of the premixed is never as good as what you can mix yourself. However, if you are just replacing a few tiles and they are not in an area where they will get wet, you can get away with premixed. With a larger job or any chance of contact with water mix it yourself - you will be glad that you did. It's easy to mix the stuff, the only real annoying part is lifting the bag and storing what you do not use.