I have a Nikon SB-800 speedlight. While feature-rich it has an annoying tendency to enter the standby mode and never return. There is a menu setting, allowing the user to set the inactive time before standby is activated. One choice is "auto" then several fixed intervals ranging up to 300 seconds (5 minutes) and finally a choice " --- " which I took to mean "never go into standby."
So far as I can tell, this menu is not connected. Whatever you choose, eventually in a minute or two the speedlight will enter standby. It does not wake up reliably and usually requires that I go to the speedlight and fiddle with it.
I have found that leaving the speedlight in the middle of the "setup" menu, rather than exiting to where the camera settings are displayed (as Nikon intends the flash to be used) will inhibit standby. This is what makes me think the problem is firmware.
Using a D70, this situation exists on and off the camera hot shoe. Do I have a defective speedlight or are they all like this?