Should I list each military posting separately or as one entry?

Usually use one entry for your whole service with your key roles listed under it, each with its own dates. This shows progression without repeating the employer many times.

Example layout:
"Royal Navy, 2010 – 2024
Logistics Officer, HMS Example, 2020 – 2024

• Bullets...

Supply Supervisor, Naval Base, 2016 – 2020

• Bullets...

Earlier roles: Supply Assistant, 2010 – 2016"

Tips:

• Give the most detail to recent and relevant roles.
• Group early or short postings in one line.
• Only list postings separately if they were long and very different, such as a secondment to another organisation.

This layout also helps applicant tracking systems and recruiters read your service as one continuous period of employment, rather than a series of short jobs that might look like job hopping. Use the same structure on LinkedIn so the two match.