>Baking LM
It's mostly for longevity and consistency. Copper will act like a sponge with Gallium, and over time absorb it. Basically it diffuses into the top layer and creates an alloy, and by doing so it creates gaps that LM previously filled. Temps might be great the first week, but over time you will notice the max temps slowly rising, as the machine thermal cycles.

>how to bake LM
I took lessons from what brother Papusan did and added some of my own knowledge to it. The amount of heat you apply, directly influences how fast it diffuses. From back when I did reading up on this, temp also play a role in the type of alloy it ends up with (from my understanding)
Which led me to baking IHS at most 115c, and using a heatgun/hairdryer on the heatsink with max heatsink temp at around 80-90c

1. You want to prepare the copper by scuffing it with high grain sandpaper, ie. 2000-2500 grain, this will speed up the Gallium diffusion into it.
2. Clean with rubbing alcohol
3. Apply thick coat of LM to surfaces you want to last.
4. Bake for 1-2 hours for IHS - Then remove tin/indium left over slurry, rub it down with alcohol, slightly scuff with sandpaper again, to get grey-ish surface instead of shiny silverish. And finally reapply fresh coat. Bake again for 1-2h, and follow same steps again.)
(For IHS, I found that depending on how much LM you apply, it tends to be fully saturated by 2 or 3 time.)
5. For Heatsink/VC, you want to use a hairdryer/heatgun, 2-3min intervals and keeping an eye on the heatsink temp 80-90c (don't want to go above 100c and ruin heatpipes or warp the VC) - it's came process of allowing the Gallium to diffuse, removing the slurry, scuffing and reapplying new coat.