Must be actual walljumps. Jumping inside a wall and hitting the block directly above you does not count as a walljump. Cramming yourself between a wall and the edge of the screen and jumping from there also does not count as a walljump.
Here is a TAS of Super Mario Bros. that doesn’t actually complete the game, but instead performs 10 walljumps as quickly as possible.
In this category, players must catch the wall and jump off of it 10 times in total. Most of the time, players would be able to perform those walljumps in World 1-1’s underground bonus room.
I perform those walljumps in World 1-1’s first pit, which seems to be a suitable place to perform as many walljumps as a TASer would like in record time. The reason why is because the gaps between the walls are 2 blocks wide, meaning I can perform a walljump by pressing A for one frame.
This is also my first uploaded TAS that doesn’t complete the actual game but instead aims for another goal.