The operations that affect the number of times a trigger can fire are after-save record-triggered flows and roll-up summary fields. After-save flows can cause triggers to fire because they are executed after a record is saved and can perform additional actions that may lead to further trigger executions. Roll-up summary fields can also affect trigger executions because any changes to the child records that affect the summary field will cause the parent record to be updated, which can then trigger the associated triggers.