I recently watched a coaching vid where he advocates for calling in the sb with JJ if there were say 5 limpers in front instead of say raising it to take down the pot. He calls it sacrificing equity and our aim here should just be to set mine and hit a huge hand. I personally raise here every time to try and isolate to one or two players and take it down post as i think this will yield to more profit. Is this bad?

JJ is an interesting spot pre- and I think either approach works...the call and set-mine / bluff catch advice is generally because even if you raise (unless you make it really big will get 3-4 callers leaving you OOP and in a tough spot when an overcard comes or when you flop an over pair and get raised on a dry flop...raising obv has its merits as you generally are ahead pre- but will have to raise big to get it H/U or 3-way and getting l/rr after a big open OOP at LLSNL is not fun...IMO it's pretty table dependent on how I play JJ as described in the OP, try both ways with 99-JJ in the SB after a bunch a limps an see what works for you

I'm always raising JJ here. How often are you flopping sets, what % of that time do you get money in, and what % of that time does it hold up? It's not as easy as hit set collect 100bb. 5 limpers + blinds is a massive amount of dead money. Sometimes you raise and win that outright and that's probably more than your expectation set mining. And if you get called, you're still going to make money on those calls. You have a strong hand after all.

One argument for set mining would be if you have absolutely no idea what to do with JJ postflop and will lose money doing anything other than check/folding when you don't hit. That's a leak that needs to be fixed but you can then truthfully say limping is the best thing you can do with JJ.

If being out of position multiway with JJ is scary just remember you don't need to win every pot, or even every third pot to be +EV. When you're against 3 other players you have to check fold a lot even though you had a really good hand preflop and that's normal. What makes people get in trouble is when they think they have to try to win the pot just because they had a strong preflop hand, and they continue with 2nd pocket in spots they'd fold flopped 2nd pair.