My first thought was that 4x1m at 4:45ish with 3 min recovery would be about right for someone looking to go sub 9:00 by spring. It’s been rightly pointed out that there are lots of variations that will create that type of fitness.
LT intervals at 5:00ish with 1 min recovery have their place as do intervals at goal pace with ample recovery (however I’d limit the goal pace stuff to 1000 or 1200.
Sub 9:00 races usually go something like 66,68,68,68,68,68,68,62. So for a race specific workout, maybe do 4-5x1k with 3 min recovery with the first 200 in 30-31 then the next 800 at 2:16. On the last rep, close with a sub 30