Are there no responses because people don't know or did the post just go unnoticed? 

there was probably no response because this is not a hot area of discussion amongst the players.  People use them at different times, and for different reasons. 

An obvious time to do them is when you're getting toward the end of the game and you just want some extra prestige to put you over the top for victory. 

Otherwise, if they are within reach earlier in the game (most of them are dependent upon the state of the game you happen to be in) you can start them then. 

Hope this helps, the game is pretty open ended, so there's not a super infallible answer to your question..

-tid242