Hrmm If I understand you correctly you might be looking for a different stroke type. There’s stroke options on the left hand of the default UI under the brush button. Click there and select the Drag Dot stroke. That will apply a single brush effect at the place you click, this works well with alpha’s and it’s size is determined by the brush size. Alternatively you can try the drag rect stroke too. This stroke requires dragging the stroke out but only apply’s its stoke once and the dragging controls scale and orientation, again this is particular useful when using alpha’s.
I’f I am misunderstanding you may also be having an issue with the lazy mouse feature which is on by default for most basic brushes as it works well to smooth out the stroke. The side effect here is that it requires that the brush travel a certain minimum distance for the stroke to start to apply. Under the stroke menu at the top, in the Lazy mouse sub menu you will find the toggle and other options for this feature. Try turning it off.