Please, consider a situation, where you find a nice example and want to copy it to your existing code to see, how it works. The indentation is almost never right right away. If there are several lines, line-by-line editing can be tedious. On another question, there were hints on how to add spaces into a block of lines and on another, how to use :paste-option, which is used to control comment-characters when pasting. (Is this right?)Can you use :paste or somehow in other way tell that when pasting, add, say 4 spaces into the front of every pasted line?Late addition: I use +gP quite often to paste a block of lines. Thus the :paste below sounds very promising. 
Pasting with spaces added into heads of lines (analogy to comment-chars)?
vim;gvim
After pasting, you can do:'[>']To shift the just-inserted text by 'shiftwidth' columns. You can repeat with ..