Triggers for transitions

What are all the possible triggers for a transition from one defense to another defense?

• Nominated on-field defender decides
  
• Disc reaches a pre-determined part of the field
  
• Offence makes a pre-determined number of passes
  
• Stall count reaches a certain number
  
• A certain offence player gets possession (eg a weak thrower)

Any others?

Which do you like? Which ones have you seen (and not seen)? I've used the first three triggers over the years.