Interesting! You are the first apart from Snapmaker that tellls to grease the rods from the outside - not even any of the manufacturers we use (and additional ones that I checked) do recommend this, since as long as the sealing lips on the outside of the carriages are even remotely up to their task, you will not get any significant amount of grease into them where it needs to be.
May I ask where you got this information from?
Regarding greasing through the lubrication holes: in order to avoid stuck rollers, it is mandatory however to slowly move the carriages slowly several lengths back and forth to distribute the added grease and to expell any excess - that is something people ignore as often as they use wrong grease.