Most game development companies have a Quality Assurance (QA) team.
I was a member of that, for Trendy Entertainment (the guys behind Dungeon Defenders 2)
The QA team is extremely efficient, allowing you to find and fix bugs before things hit live servers. But they can fail, and they can’t adequately provide how something “feels” to a large playerbase. For example, in Dungeon Defenders Eternity, we went through several variations on a certain hero because it was fun for some, unfun for others to play them; but a different hero, we all had fun playing, but when they were released the community didn’t really care for playing as them.
So here’s my suggestion: Make a public test realm. The QA team can still hunt for bugs while hunting monsters (or hunters!), but the PTR will allow a much larger playerbase to assist in the bug hunt, as well as give feedback on in-development characteristics of the game.