Mail widget does not update consistently

My home screw mail widget does not update consistently. All mail accounts are set to either Push or Fetch. The same thing occurs with widgets set to individual mailboxes and All Inboxes. It seems to haphazardly update once every week or two, but I can’t tie the update to an event or consistent timing. I have tried removing and replacing the widgets, and it has not helped. I am a recent convert from Android, and this is my main complaint with iOS. Can anyone help with this?