It is often assumed that all angels are a 'generic group', but that may not be true.
The Hebrew word for 'angel' (MAL-AKH) simply means "messenger" or "delegate." This term does not describe category or species. It is used in Scripture most often in reference to dignitaries from heaven (the "hosts" of heaven), but there may be many 'kinds' or 'categories' of these people. I think it is a mistake to lump them all into one general description, it could lead to wrong conclusions.
2 Peter 2:4 describes a group of angels that in ancient times committed a sin and were banished to TARTARUS (place of deep darkness) until the judgment. This is probably the same group referred to in Jude v 6, (referring to the events of Genesis 6). Revelation 12 says that, in the past Satan had cast down to earth a third of the stars of heaven, (possibly again referring to the Genesis 6 event). But this chapter also describes a future battle of Satan's angels against Michael's angels. Therefore it is clear that Satan's military angels are not the same angels as those already in prison.
Gabriel and Michael had to fight the "Prince of Persia -and later the "Prince of Greece" (Daniel 10:13,20-21), so it is clear that these angelic princes are not the same spirits as those already imprisoned. Thus we see that some evil angels are imprisoned, while other Satanic angels still have free access and power in heaven and earth. The present situation in heaven must be very complex and troubled, which may explain why some details of it are not allowed us to know (2 Cor. 12:4). The angel rebellion must have been very widespread -and may even be still going on. All the evil angels will eventually go into hell, which was in fact made for them (Matt. 25:41).
We know that the world to come can no more be ruled by angels (Heb. 2:5). The administration of God's Kingdom will instead be transferred to the glorified saints. We know in this present world, God's angels do not always serve well (Job 4:18; 15:14-16; 25:4-6), and that is why the glorified saints will rule over them (1 Cor. 6:3).