Hey, as always, love your work
I have a quick critique on your GoT pieces (just what I think may make them look even better, I can't say anything about speedpainting):
I think both can benefit from a little more contrast, especially around the focal points.
Fire: I think you can define some more details on the dragon, some brighter and more saturated reds will make it stand out more as the colours are somewhat dim right now.
Ice: Again, I think some more saturated blues will make for a better contrast and make the Night's King stand out.
Compositional adjustments on this one, what do you think, taking in consideration value and contrast adjustments as @watercolour suggested, (thank you for the good feedback!)