What is the etiquette for asking for updates from an artist? How long is too long? What's too short? Should the customer sit back and wait for updates from the artist or take charge of the situation from the get go? Should an artist 'punish' an overly concerned customer with slower progress or comfort the concerned that their work will be done in a timely manner? How about when other obligations make an artist tardy or potentially harder to reach?
I am opening the floor to the community on this. Please feel free to give advice on the various situations I've brought up or add to the list of potential 'what ifs'.
If you recall someone (including yourself) making a particularly helpful comment related to this topic in a previous advice post, please link to the comment (or you can copy-paste if it's your comment originally). You can also link to entire posts that match this topic.
EDIT: If you could, please add the particular type of art you do in your comment (ie: illustrator, costumer, jeweler, etc.) just to make it easier for people reading into why your beliefs are so.