Some people take that number to be an indicator of how think they might be. In general, 5000 is better than 1000, and 1 is better than 100.
From what I have seen in my experience, you can easily move the MM sitting at 1, and it is a little tougher to move the 100.
Same goes for 5000 and 10000. You see 5000 in stocks that have WAY more shares available.
I would consider 5000 easily moved with any pressure.