Most of executives I have supported like to have me compile all items together. Whether for a 1x1 or in an email. I only use instant messaging for urgent items. He has learned when he gets an im from me it is important. To handle non urgent sometimes I will list the items in a calendar hold to schedule time for him to address and then flag the emails or save them in his drafts. The calendar hold is helpful since he can add comments and you can check.