Quote (n4th4n @ Jul 19 2020 10:42pm)
the idea i had for newer players was to keep many gastly that they had traded for and when they use a lucky egg to get double friendship exp to evolve the gastly to haunter for 25 candy, and then evolve into gengars for free, but getting the exp doubled, ended up with the same cost of evolving 2 pokemon as a weedle/pidgy, but taking up half the space...
as nice as it sounds, getting exp that way is yes an efficient way, yes you are happy to level fast.
if getting 40 is your endgame goal, then go for it!
if having strong teams and be helpful instead of being helped is your goal, then never ever use lucky eggs. Having a higher level doesn't make your mons stronger, you need (obviously) dust and candies for that. Lucky eggs won't give you dust and will waste candies overall. And no, you don't make enough dust while leveling to max stuff out efficiently, you will usually end up with ~30 maxed out pokemon when you hit 40 properly, at 35 000+ caught mons. Those aren't enough for a team.
tl;dr: unless you love playing casual, don't use lucky eggs.