10 logical connections is a hard limit (see http://blogs.msdn.com/angelsb/archive/2005/01/13/352718.aspx and http://blogs.msdn.com/angelsb/archive/2004/09/07/226597.aspx for more details). If you go over this limit, it gets expensive from a performance standpoint. Also see ...

You have all seen websites where you can pick a bunch of categories by selection a bunch of check boxes. usually what you do is store those in a lookup table and then you create another table where you store all the categories for each customer. What if I tell you that you can store all that info in 1 row instead of 10 rows if a customer picked 10 ...