Depends on what you define as "many". Enigma in LK can be farmed within 20-30 hours of in-game time. It sounds like a lot perhaps, but it's light years faster than any other target in the game... certainly when running other targets without things like Enigma/Infinity.
LK is IMO the best target to run in the entire game if you fall within any of these categories:
(1) Early on when you're not that wealthy yet, to get the gamechangers as quickly as the game can offer. Meaning things like Enigma, Infinity as well as to a lesser extent (because they're relatively easily farmed otherwise) CtA and Hoto. This is a grind and dry spells can be frustrating, but it pays off for sure.
(2) Once you have all the S&Us and runewords you can wish for, it's LK time yet again. Crafts, charms, jewels, specific runeword bases from armor/weapon racks etc., again there's no better target in the game. This kind of farming is rather casual and actually quite reliable, with added benefits of occasional drune drops.
I fall into category (2), don't care much about rune drops. And I
still am surprised as to how good LK is for runes. Just one recent example: Last week I found Ber + Sur within literally 3 minutes, less than 10 runs apart. Of course I've often had 10+ hours of no high runes at all so it all tends to even out long term., but hey: That's 50% of Enigma in 3 minutes, so...