Do you use special incubator on 5k eggs?

The 5K eggs now do have several decent pokemon that had only been available in the wild (Houndoom, Teddiursa) that you might not have with a high IV, so they aren't a total loss. High IV Scyther, Rhyhorn, Eevee, Pinsir aren't bad to get either.

I put everything in the super incubators. I try to put 2k eggs in the free one but if I don't have one I'll just stick a 5k in it. I also put the egg in the super as soon as I get it. So every couple minutes an egg is hatching. If I start them all at the same time it's impossible to have 9 eggs at once when the batch clears.

No, so far I haven't. As long as I have 1 special 2k egg running, I'm happy. I'm only using super on 10k. If I run of 2k in my inventory, then I will incubate one 5k to make room

PS, I don't pay to play. Only use free coins to buy incubators. So, I don't let myself wasting them in 2-5km eggs

Right now I am using the super incubators for everything. The stardust is just too good. Unfortunately I barely care about the actual hatches since I'm pretty much set for candy with gen 1 and gen 2 mons at this point. Could always use a 100%'er or two, but that's about it.

It all depends on how much money your spending vs how many km you are walking. I would think for myself before the start of the event how much I will spend and how I use the coins. For me, I walk more then necessary for the amount of incubators I'm buying, therefore it's cheaper to buy normal incubators, taking in consideration that I never lure and for lucky eggs there will come better deals. Last year they were half the prize during an event. So I'm not even using super incubators because there its more expensive to me an the quicker hatch time is unneccesary.

I also got "tons" of 5 km eggs after emptying my egg slots almost completely before the event. Apparently Niantic thinks it is time to spend big on incubators just to get a few 2 km eggs within the time span of the event!

Yes, super for every egg. Only had time for a 2 hour walk today but managed to get som decent Pokémon. Best thing is that 8 out of 22 eggs so far are 10 km. Usually see one a month otherwise. Today's result (numbers are iv + att)

During the stardust event + the boxes that make 3 special incubators only 10 cents more each.

The answer is simple:
If you were buying normal incubators before the event, then buy the specials during it.

The 100% extra stardust you get per hatch will more than make up for 8% more cost per hatch.

That said if you dont pay for 5ks than dont :>

but I cannot afford buying so many incubators. I bought an ultra box and now I've zero Pokecoins.

What should I do?