I honestly have no idea. I use touringplans.com and if with no fastpasses the days I want to do at Disney parks don't look good, I don't do the trip. I've passed on getting together with family down there on numerous Thanksgiving and Christmas weeks for example. So to start with before ever considering paying extra for an FP, I would look for a good experience with no paying for fastpasses at all (how does the experience look with a customized plan in touringplans.com). Having been so many times too, we are willing to throw out doing certain rides to make our whole touring plan look better (e.g. for the Magic Kingdom, we don't bother with 7DMT (one and done - way too long a line for what it is and not a must do for us) and we don't bother with Peter Pan (totally not worth the line). With short lines we'd do these, but we would not ever pay extra to do these. Throwing some popular things out and doing things at rope drop can make your whole day look a heck of a lot better.)
But lol (looks like I'm a big time sucker for payng for a more pleasant experience in some cases). On our next trip March of 2022 (love the glorious March weather, but it's a busy spring break time too), two twenty somethings in our party want to do one day at Universal (park to park) and the ticket itself is already about $180 pp for that. With it being a busy spring break week and the fact that we won't be back for a long time and never do more than one day at Universal (are more into Disney/SeaWorld/relative visiting (relatives who live in Orlando and Tampa)) -- We won't be doing other Universal experiences where we would pay for them and they aren't in the financial position to go on there own, I am thinking the two of them would have a much better one day experience and get a Universal fix with the one time FP option (They are doing a Wednesday - hear weekends are even worse -- the week day, though, means that at least the fastpass lines for most rides won't be too bad). If prices are similar to what they are this year that FP will cost about $150 pp on top of the ticket. Neither the universal tickets or one one FPs per attraction add ons are in my allocated vacation budget. Everything else fits well in my vacation budget, though. It sounds literally insane to pay almost $350 a person for a day at Universal, but it helps a lot that we are only talking two people (no one else wants to go to these parks and will have other plans for that day). Anyway, these two tickets with the FPs are going to be my Christmas present to my son for 2021 (so I guess it helps me, as I typically have no idea what to get him for Christmas and this is a frivolous/fun thing I know they will enjoy). My bean counter personality checked out prices of a deluxe Universal hotel room, but that was considerably more expensive given that we are talking fastpasses for just one day, not two and we are talking just two people. If we had more people on the trip who wanted to go to Universal, there is absolutely no way we would do this for anyone (It would just be crazy price wise and we like to keep things the same for all members of the extended family (not having someone do something more elitist that others might want to do). We in the past have had 10 members in the family go to Universal for a day with a park to park tickets-- that would be a small fortune to even entertain paying for spring break park to park tickets and fastpasses for all and would be an absolute no.
We always stay offsite FYI -- great condo deals in Orlando (wonderful quality for price).