Pontius,
Ok, no harm done! You are right in the differences between AT armed and OFF.
For your question about disengaging after selecting full thrust in manual v. Leaving it on when in autoflight....I can only guess that Boeing has done a risk assessment and found that auto flight deals with the situation adequately. Whereas in manual flight you may be faced with a high pitch angle, the AT sensing altitude capture and starting to reduce and the pilot not reacting quickly enough. Liability and all.( that's just a guess on my part do and may be wrong)
Greetings
Pftt, de facto, I guess I'm starting to get confused between types as well now!!
If in fact the AT was off and you manually advanced it it will not reduce at alt capture, you are right! In the 74 with the AT off it will actually re engade the AT with the first push of TOGA and Boeing states to disengage the AT after full thrust is set.
I'll bow out now, but stand by my first answer to the OP that one push only is necessary in autoflight,because the AT will go to whatever thrust setting that is necessary to achieve the 2000fpm, whether it be full or or less.