Noobish question of odds

[VoicesSaidSo]

I'm new to poker and have a simple question which undoubtedly has a simple answer...

When the Flop comes and you're calcing your odds, why is it recommended to use your odds assuming you will stay in the hand until the River?

Why wouldn't you just calc the odds of the next card being one of your outs (the Turn), and if that misses then calc the odds of the River being one of your outs?

Wouldn't starting out by calcing through the River be giving you false-high pot odds as it would mean that you would have to stick the hand out through the River to see those odds pan out in the long run?

Hopefully I'm making this clear enough. Any help would be appreciated.

[TomCollins]

You are correct. Unless you are all in. Also, you might want to include implied odds as well.