Theory behind using flank pawns?

The c pawn is used in queen's pawn games all the time so why not the f pawn? The only reason I've heard of was it weakens the kingside but is that really that big of a deal? King's gambit is the only opening I know that uses the f pawn.

Or

These were very rough examples I just came up with but I guess it was just to illustrate my curiousity instead of saying these ideas are sound. When should flank pawns be used and whats the correct way to use them?

JSB53 WROTE:

When should flank pawns be used and whats the correct way to use them?

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When issues of controlling the center are involved there are 2 Theories:

1.Classical - to control the center, occupy the center with your pawns and pieces.

2.Hypermodern - to control the center use the power of your pawns  and pieces to control the center.  With this method  you do not create targets for your enemy.

Modern chess practice is actually a combination of  these 2  theories.

Notice that the advance of the flank  c pawn to c4,c5 controls a central square (d4,d5) without occupying a central square (d4,d5,e4,e5).  The advance of the  flank  f pawn  creates too many weaknesses around the K, that offset any  advantage of trying to control the central squares(e4,e5).  But, there are exceptions, see jengaias excellent post above.  In addition, the Sicilian Najdorf features the move ...a6.  A flank pawn move that is a very subtle indirect exercise of control over the square d5 

The other flank pawns are the  a,b,g and h  pawns.  These pawns are advanced along with the c and f pawns as the lead phalanx of a flank attack on the Qside or the Kside.  One  of the key indicators that  a  flank attack is likely to  succeed  is a blocked center.

+1

1: Flank pawns are on the same or adjacent files as a castled king and can be advanced to clear lines or open diagonals around the king.

2: Advancing a rook pawn creates a hole on only one square, not two. 

3: Taking space on the flanks allows indirect control of the long diagonals, even if the center is blocked. 

4: Pawn chains supported by a rook pawn can only be attacked from at most five directions instead of eight and can require fewer pieces to defend.