Honestly for me, it's not really their duration, it's their effectiveness. I mean, if they don't frickin' work, why are they even in the game??? ARRRGH!!! Argh Argh Aurgh1!!!! ... They are expensive and rare. Not lying around everywhere, right? They must be therefore used sparingly. So they
should be our ticket to live another day (another hour, whatever).
SBs definitely work in Fallout 3, too, and this is without any mod to enhance them. I have a couple clear memories of Janet escaping death by eating one, and one of these moments happened when she encountered the behemoth outside of Gold Grocery. You all know that one, right? We tap the baby carriage, and then out of nowhere we're being chased by a skyscraper of a super mutant!

She ate one of them while the behemoth killed her first boyfriend, Ben D. Banana. Benny tried to fight the thing, while Janet had no choice but to run &
go invisible. I remember she was able to do this, and in fact she later lured the thing back to an area where she could safely kill it.
Pretty sure they work in pure vanilla FO3 too. Cho definitely used them a couple times when his game was on Xbox, although I haven't got any clear memories. But in that case, if he'd gotten pwned while invisible and running from some huge enemy, that's a moment I'd get really pissed off, and so I'd remember that.