mm43 wrote
Total time for each message was approximately 6 seconds
I hope you are speaking about 6 seconds
between each message
(anothers planes have had to transmit own messages).
If not, It seems difficult for me to understand a so long period to transmit a few bytes, even if each "transmission packet" needs an ACKnowledge signal before transmiting the folowing.
Even if ACARS transmiting rules are comming from RTTY, I don't think a message transmission burst needing more than a quarter of second.