How many Legionaries?

So I’m working on a Creations of Bile army, and thinking about what expanding it past the 1,000 points I’ve got ready to build might look like.

I’m new to 10th, and the larger lists I see as examples feel like they run a bare minimum amount of battleline units; for instance Goonhammer’s 2000-point Bile list just runs a 10-man Cultist mob and two 5-man Legionary squads.

Are there any circumstances where you’d want to run more pistol/chainsword Legionaries to hold objectives or is that really sufficient?