3 Leles is the magic number.
Starting Lele is just the cost that you pay for having a really powerful effect, just like how running Guzmas, Choice Bands, and Field Blowers are simply necessary but also cause you to brick on your opening hand. Some decks are absolutely fine starting Lele, especially set up decks who need 2 to 3 turns before they want to even go in anyway.
If you're running more than 10 basics including Lele, the difference in odds of starting Lele when comparing 2 or 3 copies is ignorable. To that regards, if you run 2 lele and start lele, you only have 1 left to use if it's not prized. Your worst opener is also your best hand fix to keep you in the game, so you want more copies.
4 however is just excessive. The math just doesn't change enough for it to matter.