Here's my beef with the whole leak jet
Squirt duration is intended to be set by selecting the AP diaphragm with the correct length stop button on it. The timing of the start of the squirt is adjusted at the AP linkage (procedure is in the manual
The true purpose of having a leak jet at all has nothing to do with limiting or adjusting the strength or duration of the pump squirt. Its actual purpose is to completely eliminate the squirt during slower or partial throttle openings. The AP is a fairly positive displacement pump, and if the carb has just a simple AP circuit with an inlet and a discharge passage, the pump will discharge a given volume of fuel regardless of how fast or slowly the throttle is opened, depending solely on the amount the diaphragm moves. In an engine with a good sized AP discharge, this can cause there to be an excess of fuel delivered at times when the throttle is being opened more slowly and/or partially, like when you're dialing your way through a turn or a power slide.
A leak circuit solves this problem. Think of a hand pump at the bottom of a vertical pipe. If you push down on the plunger, water runs out the top, even if you move slowly. But if you put a small hole in the pipe half way up, water moving up the pipe leaks out unless you push fast enough to get it to the top before it leaks away.
With that, it should be noted that you obviously can adjust the pump squirt by using a leak jet circuit, but in doing so, you can potentially run into problems with the way the circuit is actually intended to work. This can be especially true where the output from the pump itself has been bumped way up and then an oversized leak jet used to dial it back down.