VOIP question

At my work there is currently an argument going on about network sizes. The sides of the table are as follows:

1. we will NEVER allow a network larger than a /24 due to broadcast storms this includes voip because having 400 phones across the campus will cause problems.

2. We see no reason to at least have a couple /23 or a /22 to get all the phones on the same VLAN, makes it easier to manage switch side than having one /24 per building - total of 5 buildings.

All of our networking gear is now a mix of Nexus 9K and Catalyst 9300/9400s with dual 10G links. I am on the side of put all VOIP on the same network and I ask this for mostly a sanity check - is there a known or real issue I am not seeing?