Gum printing: Longer exposure for successive layers?

I have been having an issue with what I thought was grain in my gum prints, but I now believe it is flaking. It happens only after I have already printed at least 3 layers. I read in Christina Z Anderson’s book that successive layers can require longer exposure time to sufficiently adhere them to the smooth gum layers already printed. Is anyone doing this in practice - exposing your later layers longer than your initial layers?

I am seeing it only now .. I do it regularly ..if your sizing + hardening is proper, you should not experience this issue.. I print both ways i.e. start with lower amounts of pigment [1/2 the normal amount] with 2X exposure in my unit to 2X the pigment amount and 40 - 50% of the normal exposure time in my set-up and the reverse order too.. I have done max up to 6 layers but have not experienced this issue. Hope this helps

Nope. Same time for all successive layers. No initial sizing with Hahnemuhle PR.