Boys: When does a crush go on for too long?

For some reason when ever I talk to my friends the topic of boys always come up -.- but heres the thing the topic only comes up with my friends who haven't had boyfriends yet but lots of crushes. Due to this I have heard many theroys about moving on from guys (and crushes) such as:
Theory #1 one of my friends says that you never move on from crushes you just crush on another guy and thats how you move on.
Theory #2 Another one says crushes are stupid and you can like a guy but you shouldn't obesess over him and you can like many guys at one time (which I think is healthy as long as you don't date more than one guy during a period of time) and that if the guys no interested you just gradually move on.

Whats my therory? Well its a bit of both of the above :) like and crush are the same thing in my books and mean that you are interested in a guy and its healthy if you have more than one, at times I have had one realistic (say a guy at school) and one not realistic (like a celebrity).

Now onto to the moving on part I am currently not interested in any guys and am happy being single, (I have never had any actual relationships though I have been more than friends with a few guys (which didn't equal anything) thats about it). So that rules out the moving on part of theory #1, but I do agree with the moving on theory of theory #2, but sometimes moving on isn't that easy (I should know) as guys send out mixed messages and moment they act like they're interested in you and the next they are happy being friends, so how do you move on in a situation like this? I think in order to move on in a situation like that you need to do the following:

1. Think about it and talk to some of your friends (if you can talk to some mutral friends of you and the guy you like and ask what they think about the situation).
2. Think about some more and talk to your mum (or an older friend) I mean she has been through all of this and mums do have some of the best advice on guy problems out there.
3. If you are in doubt ask the guy! You may have to do this a few times to get a clear answer but it will be worth it in the long run!

But heres another thing how long is too long to be crushing or liking on a guy? It all depends if a guy has no interest in you what so ever 1 month to 2 months is fine, but if the guy is showing interest in you 4 months to a year is normal (but not ideal). But every girl is different, but sometimes you just have to face the facts and move on no matter what your heart is saying. A crush on a guy should never distract you from your friends, school work, family, social life and mental well being and the bottom line is if the crush is doing that MOVE ON it will save you in the long run!
*please note these are my opinions I am not forcing them on anyone I just wanted to get that off my mind.
(Image is from the wonderful blog Loves Of Life go check it out :D)