Like the question states, I'm wondering if a certain amount of time must pass in-game before you're able to summon him again.
The reason I ask is this: An arena has been built, using over 500 Ebonstone, in which to fight the Eater of Worlds. However, upon using Worm Food, he only spawns about 30% of the time. The rest of the times I've tried, nothing has happened.
The message "The Eater of Worlds has spawned," or something like that, doesn't show up.
Best Answer
There appear to be several bugs surrounding the EoW. Everything ranging from his head appearing separately, to him only attacking players who aren't in corruption...you name it.
I found several forum threads, the most recent being this one (From Thursday, January 5th) with 2 people describing 2 different bugs.
The OP of that thread mentions still getting the message though, which prompted someone else to say
(Emphasis mine)
We don't get the message, but AFAICT do get the noise, so it looks to me like we may be encountering "the multiplayer summoning bug".
Additionally, James had a very good run spawning him over and over again in both singleplayer and multiplayer, so it would appear that if there is a cooldown timer, it's too small to be noticable, and definitely not what's affecting us now.