I think it comes down to your own perception of the value.
We had SF passes a few years recently when our son was going to a summer drum major camp near New England. The Flash add ons to the season passes were absolutely ginormous when I looked out of curiosity. While we paid something like $60 per season pass during a sale, the annual Flash pass add on was $150 for the 2nd tier pass! Yikes.
So, my annual pass cost for our family of 4 would increase from $240 to $840 - and I wouldn’t even be sure the extra cost would help on days I was there.
I only have experience with SF in New Jersey and New England - NE is a park where you have a much better chance of it being low to medium crowded and I can’t imagine ever buying a Flash Pass.
Sure, the few popular rides could get long on days where the crowd was a little higher, but if you rope drop or just time it in general they were manageable without shelling out a few hundred dollars.
New Jersey is a much more crowded park - I think over there on regular summer day or higher crowds you could make the argument for the Flash pass. If I knew Texas is a more crowded park (I’m guessing it is) and it is a holiday, it would get me closer to going for the Flash.
But, Back to the perception part: I personally just couldn’t ever shell out for SF park upgrades - that’s a lotta moola. I’d just look for less crowded days. I like SF for what they are, but usually the overall ambiance is lacking and throwing hundreds of dollars at them is too much of a money grab.
Full disclosure: as much of a Disney fan as I am - I’m also not of the mind to upgrade for much there either. Sure, I’ll splurge for a nicer dinner etc, but I can’t bring myself to pay a lot of money for a dessert party / fireworks spot, for example. I’d rather figure out a tactic that gives me a good chance of success and either save that money or use it to extend the trip.
So, after all of that: maybe I’m not the best person to ask.