All walls do have studs unless they are brick walls or walls that are held together by beams.
Any wood frame house or building would have wood studs in the walls to hold together the house which can be 2x4 studs or 2x6 studs depending on the house.
Most homes use 2x4 wood studs in the construction of the house.
Most studs in homes are placed 16 inches apart in all walls although it can vary in older homes.
Rarely would you find studs placed more than 24 inches apart.
Any windows and doors are also framed by the studs for support and above wide windows and doors are usually a wide header board.
When a home is framed, the wall studs are usually spaced 16 or 24 inches apart.
If you start in a corner and measure out 16 inches and you don't find a stud, you should find one at 24 inches.
wall studs are spaced 16 inches apart on center; however, they can also be spaced at 24 inches.
That said, spacing isn't always exact.
Studs can bow and twist up to 1 inch in either direction as a home settles.