Bad luck at Map drops

I't really annoying... My guildmate and I "buy" and run several maps this weekend, the only map left it's this:

all the 12, 13 and 14 maps gone

Now we have to buy again.

I'm afraid it doesn't come down to bad luck. Tier 13+ maps are not meant to be sustained for a longer period of time (even according to official statements from GGG), they're meant more as an occasional bonus. I can sustain tier 12 maps very well though it costs a bit of currency for rolling and Zana mods.

If you're running them mainly for the experience and currency, I would say that lower-tier maps give those things just as well or even better (if you factor in the higher clearspeed compared to red-tier maps). If you want to run the highest maps mainly for challenging your build, then you're a bit out of luck for sustaining them longer without buying.

The thing it's we really want to push our builds in high end maps.
I'm at lvl92 and for the nature of my skill clear some tier 1 map take the same time time than tier 12.
Actually it's before tier 12 when this skill it's useful. to run lower maps I have to change my skill.