Some user will eventually take those eggs that may not seem wanted
at first. Keep in mind that there are still users out there that
need those entries. Either way, there are two other slots that can
load more eggs. You don't need to get rare eggs all the time.
I'm neutral about this, but I usually imagine that the egg is just
waiting excitedly for someone to adopt it. 5 minutes pass, but the
egg is still hopeful someone will take it. Then 10, then 15, and
then it's optimism just wilts. I'd rather give the egg as much time
as it can to get adopted. ;n;
Yeah I have a weird imagination OTL
Art made by Charingo! Please do not
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Poke tags made by Queen Pumpkaboo!
Piggy-backing onto what Doopliss said -
All you need is patience. (which is what a lot of users on this
site lack.)
If you were to wait, they would go away or someone would snatch
them up.
Some users are hatching eggs for medal rallies or to fill up their
boxes, so those "Sentret, Wurmple, etc." would be extremely useful
to their number of eggs hatching.
Also, there's a chance you would get those Pokémon regardless.
15 minutes is enough for me, it may be a problem if you stay in the
lab for long and you want an egg, but otherwise it's not bad
some users will eventually take it
also, easy rarity eggs are common at the lab
you can't always get noibats and other rare things
the time limit isn't bad, because the lab has 3 slots of eggs, and
if all 3 are taken by easy rarity eggs (which doesn't ALWAYS
happen) then just wait the 15 minutes :)
15 Minutes is really not a long time ;) If I remember correctly, it
was set to 30 minutes a long time ago. Then it was lowered to 15
minutes.
If I lower it now to 10/12 minutes, there's eventually going to be
another suggestion, saying "Lower it to 5 minutes".
And like all the others already said: Either these Pokémon are
adopted by hunters after some time, or they are removed after 15
mins, which isn't too long, in my opinion.