@Russell ******
. Bangkok imm don't always do house visits. I'm on my 5th yearly extension. Previous 4 they didn't bother .I doubt they have the resources or logistics to do 100 a day in BBK. From what I hear they may on your first extension , or if it seems suspect.Smaller provincial offices always do house visits to my knowledge.
Regarding returning, when you apply they stamp you on for an extra period(21-30 days).
You return on that date and they stamp.you again for the remainder of the 365 days.
Date of return might vary if it falls on a weekend.