In TAR 1 to TAR 4, a Fast Forward was available for every leg, except the final leg, with the proviso that if all remaining teams had used a fast forward at the beginning of a leg before the second to final leg, then the FF was no longer available as of that point for the remainder of the Race.
On average, the FF was used about one-half of the time in thpse early seasons. The even odder thing is that since that time, the FF has continued to be used about one-half of the time. (I have the numbers filed away somewhere but I'm not in the rush to get precise at the moment.)
The primary reason why the FF is only offered once or twice a Race now is financial. The cost for some unused FF was significant, and that's one reason why their frequency was reduced. The problem is that it also changed the strategic value of th FF, and for several seasons after the change, the lead teams would always take the FF. At this point, it's rare for any team other than a lead team to take a FF, and it has ended up offering little strategic value. If it were to completely disappear, I don't think its absence would have an impact any more.
The penalties for the NELs and the U-Turns are more problematic for me. I'd rather be rid of the NEL penalties altogether, and I don't like the element of the U-Turn that smacks of the Yield, and I totally hated the Yield and was happy to see its demise.