Stuart Noble coughed up some electrons that declared:

I normally use the notched spreader over about a 4 tile area so, if a
particular tile is too low, you don't know till you've laid it and
messed up the stripes. I then just chuck a blob on top. It's like
bricklaying in the sense that you can feel when the suction is good. How
you get there doesn't really matter.

Thanks Stuart.

This place really is a mine of good tips