As near as I can tell, she last appeared in 2016, when Tim Drake was wearing the suit. She helped him in the final battle with Brother Eye. While the book ends suggesting that she died in the assault, we have no body...and we all know what that means.
So, it has been a little over 4 years since we last saw her. However, because most story lines run for 5 or 6 issues (just the right size for a TPB), that is only about 9 storylines since she last appeared, which isn't all that many.
On the other hand, Damian has shown up twice in that time, so, yes, I get your point.
It has been longer since we last saw Shriek (circa 2014). Spellbinder showed up later in 2016 than Inque, but he also has not been used since. Curare was last used in a number of issues in 2017; Stalker in 2018. In general, I approve of expanding Terry's Rogue's Galley, so I am okay with "resting" some of his "classic" adversaries in favor of new concepts. But I agree with you that Inque is do for another round.