A beginner's guide to doubled pawns positions

Hello everyone! Here is a quick guide to doubled pawns positions. First I'll describe the "decision tree", which helps to assess doubled pawn positions and then discuss particular examples. 
This guide was inspired by GM Naroditsky and Adagmator's content. Also, all constructive criticism is greatly appreciated, since I'm just a chess beginner . Let's start!

Three questions you need to ask to decide if doubling your pawns is ok:

1. Are there neighboring pawns? 

            YES (from now on mentioned as dcp - double connected pawns)

                  you do not care

            NO

                  double isolated pawns (dip) are usually weak

2. What is the type of position?

            OPEN

                  dip are bad, dcp are ok

            CLOSED

                  dip are probably ok, dcp could even be advatageous

3. What's the stage of the game? 

           OPENING

                  if this doesn't hinder your development, you are totally ok,

                  you'd have a lot of chances to undouble the double

           MIDDLEGAME

                 you are ok

           ENDGAME

                 doubled pawns are bad

So, let's recap: doubled isolated pawns are generally bad, doubled pawns are weaker in open positions, since it is much easier to target them, doubled pawns are bad in the endgame, but in the opening and middlegame you generally do not care.

Now we discuss particular examples, starting from good dcp structures.

This one is a common position in sicilian games at my level (1300). Black has a really nice position, controlling the center with d5 and c5 pawns, c6 nicely supports d5 pawn. Doubled c-pawns are even advantageous.

This could arise from queens pawn positions when white goes for an early trade of dark squared bishop for f6 Knight. Here black's King is very safe, you would never worry about king's safety.

Common Italian game position, which could be achieved by both white and black. e3 pawn nicely defends d4 and f4 squares from opponent's knights hoppind around, supports future d4 push and gives you semi-open f file. Doubled pawns are totally justified here.

Amazingly, this position arising from KID vs London is totally ok for black! (hope I didn't mess up trying to reproduce the position by heart, there was a game by Danya Naroditsky in 5 min speedrun, where he explained this very concept) Black traded their lightsquared bishop on f5, white said "Aha! You weakened your kingside!", but black closed the center and proceeded to attack along semi-open g-file. Here doubled pawns helps you to keep the position closed.

Now we discuss bad doubled pawns examples.

Let's discuss doubled pawns that hinders your development in the opening. This position occurs in a Bayonet and Tal variations of a Caro-Cann. White goes for a positional pawn sacrifice e6! Look at black's darksquared bishop. He is so sad. Black will have a hard time developing him.

This is an example from my game. After I planted dark squared bishop on d4, white's dsBishop is toast, white will need at least 3 moves to develop it, while I've spent only one move, supressing it's development. This time gain helped me win the game relatively easy.

Another good example of doubled extra pawn hindering development is a Nf6 Scandinavian. If white tries to be greedy and hang on to its extra pawn, black gets huge lead in development. d5 white pawn is hardly defendable: queen does not support it because its doubled.

Now let's discuss isolated doubled pawns structures.

In situations when the middle of a connect-three parn chain is undermined you never take. Pawns in the corners of a 3x3 square are incredibly weak, if there is no pawn in the center of that square.

And the juicy part: tripled pawns! Since tripled pawns are 99% percent isolated, they are always bad.

Recap: 

1. Isolated or not?

2. Open or closed position?

3. Game phase?

Bonus question: what to do with doubled pawns?

I'd say that you shouldn't hesitate giving one of those up, because doubled pawns are hard to protect. If you have a chance to undouble the double - definitely do so.

Thank you for attention and have an excellent rest of your days

PS. Again, all comments and improvements suggestions are greatly appreciated.