a few days after follow up mode was rolled out i showed my mother how to use for adding items to the shopping list. she, we only needed to say alexa once and then just keep adding items. the only time our mom needs say alexa again at this point is if she waits beyond that five second window to add the next item.
as for follow up mode in general i have found it to be somewhat spotty. for the exact same command sometimes follow up functions as expected and then other times, again same command verbatim but it doesn't activate? i expected a few hiccups at the outset. i expect in shortly that updates will make it all more seamless, less quirky.