"Is this the most optimized configuration?"
Depends what you believe is optimal which depends much on the needs of the networking application to be supported and the network hardware to be used.
The camera hosts will only send a unicast video stream to a recording host? If so, very likely using even single VLAN for just those hosts, as a /22 (or even larger) would be fine too.
Conversely, on a L3 switch, even if each camera host was routed as a /32 network, wouldn't make much difference to the switch.
In other words, forwarding, in a L2/L3 switched environment, for camera hosts, isn't much, if any, impacted by number of hosts, number of VLANs, subnet sizes, or L2 vs. L3 forwarding.
Does this mean there's no concerns? It does not!
You didn't mention bandwidth consumption of each camera host, both now, and possible increases in the future. There can be a very huge bandwidth difference in low def black and white vs. high def color.
Then there's issues, like raised by @Leo Laohoo , i.e. the camera host "quality".
Although you've focused on the camera host aspect, there's also all the similar considerations for all your other network hosts.
So, is your network design optimal, cannot say; insufficient information.
As to your questions about having your network devices support host NTP queries. First, realize supporting NTP, at all, takes processing resources that might be used for more specific networking purposes, so, ideally, you don't want to use such without reviewing need and alternatives.
For example, what if you configured a time service server? That off loads some complex processing from network devices. Yes, a network switch may still need to forward time information between hosts, but switches have dedicated hardware for that. They normally wouldn't have dedicated hardware to service NTP queries.
As an alternative approach, possibly you take advantage of the NTP architecture, i.e. you distribute the NTP servicing.
Basically, you're asking, how many direct NTP hosts can I direct to my main switch. My counter question, why not consider an alternative design, which dramatically reduces discovering what straw number breaks the camel's back.
BTW, I doubt what you have have is "bad" or courting immediate failure, but to fully optimize a network often requires deeper considerations beyond just using /24 subnets.
I'm also not suggesting an "optimal" network is a requirement. For example, again, if you want to use /24s, and if there's no real downside, go ahead and use them.
Anyway, IMO, the real "best practice" is considering your requirements and trade-offs you may need to make.
Remember an industry "best practice" is like buying a suit off the rack, which may be a perfect fit or far from it.
