Think of it like this.
You watch TNG, and all the leads are bridge crew except Beverly, for obvious reasons. Later after Wesley is gone, it's still most of the bridge crew, or rather most of the primary manned posts.
VOYAGER, same thing... each main post is a lead character. (Helm, ops, tactical, captain, XO.) Same with ENTERPRISE.
On those shows, any time those leads were elsewhere and someone else was manning their post, virtually every instance was with an extra with no name. Or any dialogue.
Now comes DISCO, where you have the only bridge leads being the captain and XO, and everyone else has a name and dialogue. But they are not really given much, despite them already having a big leg up on previous shows.