I started in 2009. I have ran Tempest Keep and ICC on weekly CD and never seen the Feat Of Strength mounts fall. Not for me, not for an alt, not for a transmog group run. Nothing. I believe I will never see those mounts and it tilts me. How many months and years played doing the same task over and over to make no progress while paying for the luxury burns me something.
Just so you know, when Timewalking raids for those expansions roll around the weekly quest to clear them has a very high chance of dropping those exact mounts: Wrath of the Lich King Timewalking Guide - Wowhead
Maybe set your sights on that 
Also when I farmed ICC and Tempest keep for the mounts, I ran it on like 8 alts - you’ll want as many bodies as possible farming to improve your odds.
It is a double edged sword for me. I never liked subscription based games as they tend to make me more goal driven and focused on the title with the sub than anything else. When I played wow hardcore I had the works, alts and willing friends to help farm rare things. TLPD was less of a headache than raid drops. I did not know timewalking had increased odds, so I can blame myself for not looking it up and being ignorant to the mechanic.
For this old knob I only know what became regular, and I had a sort of break in my head where I was wondering why I continue to pay for a game that takes all of my free time and never drops after a very long time playing the few objects of interest, It cripples my motivation to play past the expansion and finally be done with this entirely.
When I was using Steam and had free time I could do many games like Dota 2 and CS:Go and Warframe and Killing Floor etc etc, and after the fee, most was either pay and play once or free. When I play a sub I can’t waste even a free moment as I am already flushing income down the drain with time and patience being shoulder demons and angels.
I think Ill try for my 110 exalted and really check my options. When a game stops being pleasurable and more a chore that bothers…