This is not a question we can answer for you. You may get lots of opinions (which are off-topic here), but ultimately, you need to base your decision on your organization's security policies and practices.
Remember, the benefit of having separate VLANs is so you can apply policies (access lists) to restrict which traffic is allowed on the VLAN. You should consider:
- Are you restricting traffic on the management VLAN with access
- Are the servers managed by different administrators?
- Does your security policy prevent them for accessing network
If the answer to all these questions are Yes, then it may make sense to have a separate VLAN. Otherwise, there's not much point.