I'd say 3'-5' is borderline, maybe ok if your at an all sandy AO that you don't want to throw beyond the breakers anyhow, like Pismo for example but anywhere near kelp and it's going to be salad city.
As far as how much lead I throw, especially with sputnik now the norm, I base it much more on the the sweet spot that my rod will throw best rather than the actual holding strength of the weight. 90% of the time I'll throw 5 oz or 6 oz + bait depending on the weight of the bait. Even if it's 1' -2' I'll throw 6oz + bait even though I could get plenty of holding power from a 3oz or even 2oz sputnik, but my rods won't load properly, if at all 3 oz.
Now of course there are those times rare times when 6oz sputniks are not enough to hold so I'll step up to 7 , 8 or even 10oz sputniks, even though thats pushing the top end of what my rod should be throwing and for sure out of the sweet spot. That being said I think it a rare case when throwing 10 oz of lead will solve all issues and make it easy fishing. If you need to throw 10 oz to hold,thats a pretty good indication that things are pretty much going to suck.
JOE