How long my tests are queued and is there a limit on queuing tests?

The wait limit for the execution of a pending queued job is 15 minutes. The test gets cancelled if it exceeds this limit.

Queuing manages to run some limited number of additional tests other than your subscribed limit. Accounts subscribed with up to 5 parallel tests can queue 5 tests. Any subscription with beyond 5 parallel tests can queue an equivalent number of tests.