Just as most people have said, buying packs will always be the more fun option. But also buying singles will usually be the most cost effective, unless you have insane luck with your booster box(es) or choosing packs from the store. Haha.
When I started collecting, the internet was still in somewhat of a stone age as far as pokemon goes. No Facebook, Instagram, etc. You had eBay and about 5 you-tubers that regularly made pokemon content specifically about cards. I still tend to want to be stuck in that era because cards/packs/boxes were cheaper, and mintier too… Nobody was about making profit back then except card stores. Every booster box was sub $300, and a young teenager whose only income was mowing the lawn and shoveling snow could actually afford those boxes that are now in the thousands.
Times are now much different, and buying packs is no longer as cheap, nor is it as much fun. Maybe that’s due to growing up, or price increases or the way that sets are made now. I think it’s a combination of all those factors, plus maybe some internet influence as well. I had always pulled my cards from packs as a kid, or traded for them from friends or online. It took me to get to 5 cards or less before I really broke down and bought the singles I needed for the set because as we know, it’s no fun buying singles. Anyone with the money can just buy them, and it takes away from it being a challenge. But sometimes, when you mull over the options, it really is the best one to choose.
So in short, what I do now is what I think a lot of people do. Buy one box, have some fun opening it and get most of the set out of the way, and then buy singles/trade after that. In my opinion, It’s worth the shot of buying one box to try and pull some of the most expensive cards before having to shell out the extra $$ for them anyways (this is only concerning newer sets obviously haha). Unless you’re in the business of selling cards or collecting bulk, I don’t think more than one box is necessary.
Madison, one really good advantage about opening a box when you’re a set collector is that in ensures that the whole common/uncommon/rare set are in close to gem mint condition as possible. Of course there’s a chance it’s not always gem mint, but the odds are greater than ordering singles and expecting the same thing. Pack fresh is a lucrative term, but there’s a reason why people open packs rather than buying singles when trying to send cards to psa. I think I’ll have more believing me than not when I say that even 8 years ago, ordering singles from troll and toad or ebay still resulted in disappointment half the time. You just know if you order a complete set of commons from any old set past like 2002, like fossil for example, it’s more than likely going to look like played bulk. Lol, but there lies a new challenge with completing older sets of which I am not used to. My own older sets were mostly complete before these issues arose, but I hope this gave some insight at least. 
