From what I recall, all manufacturers manuals for aperture priority capable cameras list a short exposure time but most of the cameras that I tested react differently. Of these cameras, only the Canons actually limit their exposure times to 30 seconds. Minolta varies model to model randomly and never had one go past a minute or two. The Nikons tend to go well over a few minutes but not repeatable and varies randomly. My FM3A has managed to get over 10 minutes but given the same controlled lighting, it varies randomly, The Olympus OM2 can go to 19 minutes subject to settings ->
http://zuiko.com/web_5__20150924_032.htm.
Pentax varies according to models but I have found the only camera that can go for hours repeatably to be the Pentax LX. I have tested both of mine to aperture priority autoexpose a scene lasting hours long.
Here's one showing 15 minutes on Kodak Gold 100 under controlled lighting.
This one was > 40 minutes on Kodak Ektar 100
I even made a "long shutter indicator" by using the LX's flash port with a battery and LED that stays on while the exposure is being made and turns off when done. This way I didn't have to look through the viewfinder every so many minutes just to see if the mirror had returned. Comes in really handy for exposure lasting hours.