how rare are mega taiga and mesa biomes

I have literally (just counted) traveled over 25,000 blocks on horseback + running in the over-world searching for these two biomes and they are no where to be found, any ideas of how rare they are or how to find them,

yes I am very far away from spawn and the terrain I'm searching is being generated in 1.7

I have been thats how i tracked my block count and how Ive been able to find my way home,

Thank You though

I guess I got lucky, my first trip out into new chunks I found a mesa biome.

u must have,

i tried a new single player world in creative and could not find any mesas or mega taigas

i have traveled 40,000 blocks on emc now looking for those two biomes

Update

Just found a mega taiga, its freaking huge

that is after exploring like 40-50K blocks all i have left to find is a mesa so i can make a multi base settlement that goes across almost every single biome in the game

I believe the smp3 wasteland south west spawn is in a mega taiga.

thanks dude, i just found one though

that mesa though

found a tip online stating look around similar tempurtured biomes, bout to go check near all the deserts I've found

SMP2 North East has a Mesa, and taiga. (They're not big, and probably scavenged, but theirs still a lot of acacai trees and clay blocks left.

Thank You for the tip ill check it out