I'm more surprised they never touched the Cathedral Altars for all cities...

[Kai]

The buff you get from these are only granted each day, but has a duration of 300 seconds.

That's roughly 5 minutes and is sufficient for actions within the city itself such as if you fight in it.

But fast travel anywhere after this or run around outside to a dungeon and that buff is almost gone by the time you enter one.

I think the only benefit is if it lasts longer than 300 seconds, like 900 seconds would suffice for 15 minutes.

48 real minutes = 1 in-game real day, so a buff giving us 5 minutes is really short.

1200 seconds is probably a good value for this. And modding might be simplistic though some mods could conflict as it's a buff effect.

[Kai]

Not to mention that the buff they give is very small, so it's not going to make a difference if you have alchemy granting you multiple 25 str fortification on demand lol.