It is not uncommon to have a place or two in a house where building up plaster is necessary. An obvious example is when spaces between the bales are left un-stuffed. Some of these holes can seem like never ending pits when you start laying plaster into them.
For that reason, it is important to be very thorough when stuffing the bales. That does not mean fill every hole with the end of a screwdriver; however, it does mean that every hole needs to be addressed.
One place where plaster build up happens that is not as obvious is around windows and doors. It is not uncommon for a window to be set in the framing and the bales are left a bit further back from the jamb than desired. When that happens, you will need to add plaster to make up the difference. When you do this, be sure to add some plaster lath (blood lath) into the mud if it is thick enough to allow for it. If the mud is not thick enough to adequately cover the plaster lath then use fiberglass tape (like drywaller’s tape) and embed that into the plaster.
If you don’t reinforce the mud that you build up, it will crack. When plaster gets too thick, it cannot support itself and cracks. Take the extra time to add the reinforcement and you won’t have problems. In addition, make sure to add the plaster in lifts (layers) allowing for each lift to dry adequately before the installation of the next. If you apply the mud all at once, it will be too thick and will crack while drying.