This depends on which policy you have as the single trip duration for each provider is different, please check your policy wording.
If you have an annual policy with Collinson or National Breakdown, the maximum trip length under the policy is 90 days.
If you have the annual policy with Allianz Global Assistance, it's 31 days.
This means that you can take as many trips as you like within the policy duration providing one trip doesn't exceed the limit on the policy.