From my own experience it doesn't matter, as long as all surface is covered without air pockets you're good. It is definitely better to err on the 'too much' side.
I remember one of the YT channels did a test of multiple ways to apply TIM and the results were basically all the same barring too little
Yeah, a little too late for me now. I think a contributing factor are some of the thermal pads which may create a sort of lever, lifting the heatplate, so I'll replace at least one them with k5pro - that's a thermal paste, but with play-doh consistency, suitable for large gaps.
I believe this GL703GS & Zephyrus uses K5 Pro on VRM's etc. opposed to pads, as first tear downs made a "thing" of it. In reality it's not been a problem. I've had no need to completely remove the back so no idea if it migrates over time, equally the thermals are good. I also believe that ASUS uses a different TIM for the CPU & GPU dies, however don't know which brand.
I'd be inclined to drop the pads, use the K5 Pro and a known good TIM for the dies. Might be worth checking the cooler against a glass surface in case it's deformed. Must admit I don't care for the retention system as not only tri point which is known to offer uneven pressure, the securing points are on tags that are located away from the dies.
nb. GL703 series has an access bay for RAM & SSD etc.
Q-6