In the case of Gloria, she should have some amount of slack to figure out how to do the big picture items of her job better, which include how better to help Tony.
Where things get tricky is when looking at the whole organization there's been a long tendency to see "slack" as "fat" that's to be trimmed. So, if a organization has two Glorias who both have some slack time, the argument is the organization would be more efficient and profitable having one Gloria with less or no slack time.
This has worked for corporate profits, but it leads to the humans in these positions unable to have the slack time needed to improve those positions.
Sometimes, this is fine and you can build a very profitable business off of it. For example, McDonald's isn't looking for their frontline staff to do any thinking.
In general, if a position can exist and doesn't need "slack" time, it is probably a position that should be automated as soon as it's cost effective.
If you really need a human to do it though, you should stop trying to treat it like machine and realize the importance of slack time and build it in to the schedule.