All validators must pass in order for a transition to complete. Currently an issue will fail as soon as one validator fails, without running subsequent validators. The disadvantage of this is that it staggers the error messages.

For example in my transition I have several validators, in this order:
1. Fields Required (About a dozen fields must be filled out)
2. Date Compare (I want to validate some date fields)
3. Comment Required (Using a custom plugin I ensure a comment is entered)
4. User Picker Validator (Using a custom plugin I ensure a user picker has a minimum number of users selected and that they have been selected from a particular group)

When a user submits a ticket in violation of all four validators they only see the error from 'Fields Required'. When the required field is added and they resubmit they will then see the error from 'Date Compare', and so forth. The overhead of running all validators is low and, while not logically necessary, having the ability to display all error messages simultaneously would enhance usability.