Yes, typically with an eye for how it might serve as a (bonus) advantage in some fashion.
"Oh ho, if Fleebox the Great famously drowned, maybe we should summon water to flood his tomb and freak out his ghost!"
To your original question I think giving advantage if they have multiple relevant skills would work fine and not break things. Especially if you're applying this to knowledge checks for "extra" info. Instead of rolling your religion and your arcana and your history and whatever separately you're moving it into one roll and taking it as the totality of their knowledge about this thing, giving a boost if they have multiple relevant areas of knowledge. I like it - it's probably a bit cleaner than what I do.
What works for me is that any time they make a knowledge check where there's something to remember/glean/research they always get something from it unless they roll a 1. A failure on the check gives them minimal information, a success on the knowledge check gives them more information, but they can only roll once as they're fishing for clues like that. And to make it work I have to be able to be flexible with giving info out - I can't sit there and think "well they're using History for this check, but some of this is about Wizard stuff so that stuff should really be Arcana so they shouldn't learn anything" - because then I'm just encouraging them to try to play "guess the skill the DM wants me to use" with their knowledge checks. The deal is that succeed or fail it's all they're going to get on their end and on my end I always have to give them something meaningful whether they succeed or fail (unless they roll a 1). I limit the skill they use, usually by giving them a few options and letting them decide which way they want to approach it.
You use the help action for multiple people wanting to do the same kinds of checks, and that's a good idea. What I will do instead is have everyone who wants to make the check for knowledge tell me what they're trying to accomplish (to determine the skill they're using) and then roll at the same time
but only the highest roll matters for determining what info they get. If they're all researching for the same kind of advantage in different areas, they can all use different skills to do it, but the roll happens once, they learn everything they're going to learn from any knowledge checks, and then they move on. If multiple people succeed I can throw more out there if I'm improvising, or I can use who succeeded and what skills they were using to color the info I'm giving out if multiple succeed, but the knowledge they get is all they're going to get.
IME these two things together cut down on a lot of "well what do I know from my studies of history? (roll and fail) How about my arcane training? (roll and fail) What about my comprehensive knowledge of religions - any cult activity here? etc." types of scenarios which I think is what you're describing. But I think advantage if you have multiple skill proficiencies would work well. I think the key for me is to communicate with the players that they get ONE knowledge roll and that's it - that represents everything they're going to know about whatever it is they're trying to research and then move on to something else (and then the obligation on me is to make sure that I live up to that on my end).