OOOOOHHHH NO, don't do that. If you watch 5 and then skip to 8, it'll be somewhat confusing. Compare with watching Mission: Impossible 1 and skipping to Fallout (or thereabouts).
But to put your wallet at ease, if you want 5 you're going to have to buy the collection (it's not available individually) so you get all 8 anyway so, well, you may as well watch them. And if you get them off Zoom with the discount they're little more than a tenner each, which ain't bad for 4K... (and yes, for different reasons, I'd say 1 and 5 - 8 all look excellent).
I have to say, 6 is a guilty pleasure tie for my favourite. So ludicrously OTT in terms of delivery, but deeply satisfying as a fan nonetheless. And 7 WILL make your eyes well up, which is crazy to think about in an action franchise.
Damn you, I'm going to have to watch them again now, having just watched the first five over the weekend. Damn you.