What i usually do is to adjust all my torp depth and speed in regard of target (s) and then exit the periscope view to open all needed tubes with the conning tower buttons (the ones just in front seat, or the ones on the wall box)
When opened, they are kept open
(unless you click other tube in periscope view to make changes - you’ll have to re-do again)
Then i can fire all my torp one after each other without wondering to open tubes...
