Psalms 91:1, 11 says, “You who live in the shelter of the Most High, who abide in the shadow of the Almighty . . . he will command his angels concerning you to guard you in all your ways.” If they are to guard us in all our ways, we’d need to have constant attention.
Matthew 18:10 says, “See that you never despise any of these little ones, for I tell you that their angels in heaven are continually in the presence of my Father in heaven.” When he says, “their angels,” this suggests that they have personal protecting angels.
When Peter was brought from prison by an angel in the Book of Acts and came to the house where all the believers were praying, he knocked on the door and they didn’t believe it was him. They said it must be his angel. Not “an” angel, but “his” angel (Acts 12:15).