subnets vlans and routing

Hey team, looking for some guidance on this design i'm doing.

I am in the process of a network migration of sorts.

Started off with a sub-basic network setup, which goes:
[wan] <> [utm] (vlan1 192.168.0.1/24) <> [routing switch] :
(vlan1 192.168.0.2/24) <> [servers]
(vlan2 192.168.1.2/24) <> [clients]

Now I am moving most/everything into the 10.x.x.x space, using that flexibility to setup different sites under its own octet, different purposes/types under another, etc.

My question is, as I reprogram switches and routers, assigning them a MGMT IP, should I use this MGMT IP on the UTM router to route traffic from the Routing switch, or should there exist some sort of routing subnet/vlan?

For example, using only a mgmt vlan:
[wan] <> [utm] (vlan12 10.1.2.1/24) <> [routing switch] :
(vlan10 10.1.1.2/24) <> [servers]
(vlan11 10.1.10.2/23) <> [clients]
(vlan12 10.1.2.2/24) <> [mgmt]

Or do I add a routing vlan? :
[wan] <> [utm] (vlan13 10.1.3.1/24) <> [routing switch] :
(vlan10 10.1.1.2/24) <> [servers]
(vlan11 10.1.10.2/23) <> [clients]
(vlan12 10.1.2.2/24) <> [mgmt]
(vlan13 10.1.3.2/24) [routing]