As an ESOL teacher I collaborate with many different classroom teachers. Ideally we would have ample time to coplan together. Typically what ends up happening is I stop by a classroom for a few minutes in the morning. Things are rushed as we are both trying to get things ready for the day.
This past fall my husband (who is a 2nd grade classroom teacher) implemented the Daily Five in his classroom. We worked together to look over lessons and develop resources together. We joked that this is the kind of co-planning we both wish there was more time during the school day to do.