HTTPS is used to protect the connection against sniffing, manipulation and against impersonating an endpoint. How much this protection is needed in your local network depends on how much you can trust your network. As always, there is no absolute security but one has to find a balance between the achievable security and the remaining risk considering the amount of resources (money, time, people) needed to increase the security.
For example if you have a local network where a not fully trusted person (or a compromised machine) could use ARP or DHCP spoofing to redirect the traffic, then use of HTTPS on the internal network could be used to protect the traffic anyway. But maybe a better investment would be to increase general security of the network in such cases. If instead all machines on the network are properly authenticated and IPSec is already used to protect communication on a lower layer than adding HTTPS on top of this is less needed. But it still can be used as a defense in depth measure, especially if the lower layer protection (IPSec) is managed by different departments or governed by different security requirements than the higher level protection (HTTPS).