Advice please- adhesive under crack matting, how important?

[bsc ceramics]

I agree with @3_fall on the 1st pic no ady squeezing between the two
rows of mat and the leading edge defo has none under it. O dear!!

 

[WetSaw]

Definitely loose laid the mat. Look at the doorway on day 2 and the curl on the edge of the mat on day one. As others have said, especially Mr Clean ( 3_fall) , there's always a bit of adhesive that squeezes out.