Actually... you can do it in 6 days if you have some spillover rep from the last tier. First of all, 50+3*35+2*29 isn't 207, it's 213. 213*6 = 1278. The most spillover you can get is 70, though you only really need 42 to do it in 6 days.

That said, let's say you did three quests of the previous tier each day and only two of the last tier four days out of the six, and the above two days out of the six. Chances are good that you won't get High Wind all six days (though it is possible). In this case, your progress will be: 70 + 207*4 + 213*2 = 1324.

Now, if you don't have any spillover rep, the above post applies - it'll take you 7 days no matter what.

So, yes, High Wind is especially difficult for no reason and probably shouldn't be. It is really not easily done at level 16, even if all DoH classes are level 16. But, you can avoid it. There is another quest with the same quality requirement, but I think that one disables cross-class skills instead, has an extremely low progress requirement, and you only need to make one of them.

One last note - for those who are struggling with the Ixali quests, especially High Wind, have you tried using crafter food? Even just NQ Frumenty (~10 gil at NPC vendors, +10 CP) could really help...