On Prime minicomputers back in the 80's, there was a disk controller order to format a track. That's what broke it into sectors and put sector ID fields into each sector, in whatever way the disk controller wanted.
A read was in 3 parts parts: first do a seek over the right cylinder, then select a head, then read a sector. That least part read everything spinning by until it saw a sector with the correct sector ID.
Sectors were not in block order because if you read sector 1 then tried to read sector 2, it would have already spun past the head, meaning sequential sector reads would require a complete revolution of the disk.
So instead, sectors were interleaved with a skip. There were 9 sectors on a track, so the sector IDs might be written as: 0 3 6 1 4 7 2 5 8. You could read 3 sectors per disk revolution instead of 1.
A read was in 3 parts parts: first do a seek over the right cylinder, then select a head, then read a sector. That least part read everything spinning by until it saw a sector with the correct sector ID.
Sectors were not in block order because if you read sector 1 then tried to read sector 2, it would have already spun past the head, meaning sequential sector reads would require a complete revolution of the disk.
So instead, sectors were interleaved with a skip. There were 9 sectors on a track, so the sector IDs might be written as: 0 3 6 1 4 7 2 5 8. You could read 3 sectors per disk revolution instead of 1.