When and how to add garlic to a dish? I want to make some chicken with ginger and garlic, and every recipe I look up puts the garlic in at a different time.

In Korean food, it is grated into the marinade.

In India food, it's mixed with ginger and ground into a paste that you cook down and then mix into curry.

In American cooking, you saute it after sauteing some onions in the fond/fat left behind after rendering the chicken.

In the specific Chinese dish I was looking at, you throw it in right at the end of stir-frying the pork. (video here: https://www.youtube.com/watch?v=uhYEy3PA0RI). 

In another thread on Cooking StackExchange, you flavor the oil in the beginning with it (no mention of taking it out).

So my question is, garlic do you determine when and how to add garlic to the dish?

I imagine the answer will be "depends what you want to taste", so if you can answer how it makes things taste, that would be great!
The key is to understand what impacts the flavor and texture of the ingredients your using.  Then, to use the appropriate techniques to achieve the result you are looking for.  If you keep a peeled clove of garlic whole it can have an aromatic effect if gently cooked in oil.  Smash that clove and the effect is more powerful.  Brown the clove, and you will get sweetened and caramelized notes...go to far, and it will take on a bitter note.  Slice the clove and the effect will be different.  Smash and chop (or grate)...more pronounced and more integrated. Roast without peeling...sweet.  ...the list goes on...

Greater cooking experience will allow you to understand all of the potential nuances that different cutting, crushing and cooking (or not) of garlic can bring to a dish.  Then, you can understand, adjust, and/or create the recipe you are looking for.