I, uh, was referring to wild battles in the first place. The point to fighting wild Pokémon is to get experience, so I don't see why them being short is a bad thing. Also if you could explain your "outdated method" reasoning, I'd appreciate it. If a 'mon is in battle, it'll get all the experience possible now; if it isn't, then it gets half. I'll take all over half any day.
In gen 1, the EXP all was a worthless item, so in order to level up pokemon you had to send them out first and then switch them with an attacker to take a hit. This was a very repetitive thing to do in every battle and they didn't even gain much levels because of it. In future gens it got better because the EXP Share held item splits the XP between two pokemon, and in XYORAS it got a bit rougher by returning to the EXP All system, but it actually gave your enough EXP to level up (at the expense of the game being made easy.) This combined with lucky eggs made it easy to gain levels quickly, especially with it off.
While I'm super happy they returned to the Gen V level scaling in favor of a good challenge, the scarcity of spots to level up your pokemon in general (much less to level 100) is glaring, and while typically the EXP share (whether it's on one pokemon or all of them) helps to spread the experience to everyone, focusing on one gets risky unless you're at a higher level.
Sure, I could send out my defenseless level 1 Bagon to fight a level 59 bewear, but what's the point if I'm pulling it back in favor of a Pokemon that can actually damage it? To me it seems pointless since the EXP share would do the exact same thing without the switching but to more pokemon. My point is that lucky egg or no, you aren't really going to be seeing much of a fast level up unless your pokemon is capable of taking down those enemy pokemon on their own, either with FEAR or destiny bond, which is why I found fighting the poni gauntlet trainers helpful as they gave me more experience but won't let me rematch them.
It's somewhat simple to level your mons up to level 50 in SM with your method, yes but now we're back to having Level 100 be a mythical phase when XYORAS gave you places to fight high leveled trainers for that purpose. Part of me thinks that golf course was meant to be this region's Battle Chateau or at least a good place to level up but we can't go there, leading to this issue.
I mean, sure you could argue that going to level 100 in an age where they round stats down to level 5r0 isn't a big deal, but with those bottlecaps requiring level 100 pokemon for some stupid reason it kinda defeats the point if its hard to reach that level. With my level 84 Necrozoma I tend to gain about one level for it during a E4 rematch with the EXP share on, and MAYBE close to two with it off. If I have a lucky egg I could gain a few more levels, but unless you somehow get boosted EXP by having you loan your mons to a friend it seems harder than ever.
