They tended to come in moments of more extreme battle, or when he'd worked at something in training for a particular length of time. Of course, there were times that they didn't come at all either, much like the Quests that Vol had come so used to.
The System, and the stats that it offered were almost a sad shell of what it once before. It appeared to be doing whatever it could to offer him all the progress that it could, as if desperately reaching for what it had access to, but it wasn't nearly enough. Vol could almost feel it begging for the sort of transformation that it wished for – in the same way that Pandora had urged a transformation in Vol's Summoning, by first taking something away from him.
The same was true of his Command System. There was something new to be had there, and he thought he was seeing something new in the way that his officers were developing, but he still didn't have enough information to make use of it.