Every floorplan and brand is different so this is going to get confusing. However, on the 303 LaCrosse example above (only the 303 LaCrosse above) the kitchen and bath grey tanks are plumbed together ahead of a single dump valve (not termination) which allows these two tanks to equalize together. Thus, there are only two valves - one for black and one for BOTH greys - on this model.
The 303 is a rear kitchen so the galley tank is a LONG ways from the termination. The slope of the drain line is minimal so it's not uncommon for the galley tank to take a while to drain. If you're hitched up and have a slightly raised nose, it would take even longer.
Not to be evasive, but this thread could really get confusing for everyone if we try to address individual situations. If there are questions or concerns on your unit, please go to the web site at www.primetimerv.com
and use the CONTACT US link to email our Customer Service Department regarding your particular situation.