So I did my 10 x 1000 last night with a 400 rest between.
I successfully hit all my 1000's at or below goal pace but for the last few repeats I needed a longer rest between. I started out the first 5 at 2:15 but by the last one I was shuffling along at close to 2:30. Is this OK? The 1000's never deteriorated, though the last one definitely took some focus to get through.
They were all around 4:00.