Whenever the coast is clear to pass, I pass. Whenever the coast is not clear and safe, I don't pass.

If waiting a few extra seconds will deter any mishaps, I'll always opt to wait...Safety trumps urgency every single time!

Besides, usually the "urgency" is only in your mind...

PS.

For long or extended wait times, I dismount and walk my bike towards the front in order to better assess the situation.