In my experience (during high season), it has always been 1 hour in AM and 3 hours in PM. I think the up to three hours is just vague on purpose in case they want to change it at any point. You can bet on these times unless you hear otherwise!
Just moved to San Diego - more DLR trips here we come!!
DLR 2004, 2005, 2006, 2008, 2009
Disneyland Paris 2003
WDW 1997, 1999, 2001, 2001, 2005, 2006, 2011 (DH's first trip)