Much depends on the training regime a horse has gone through.

In the UK it is more common to race for fitness over 1600 or 2000 as a first up run - not seen very much here.

I can also remember a Mike Moroney trained horse coming across from NZ a few years ago and landing a plunge first up over 1600 in South Australia.

I think he commented (in retrospect) 'Nobody in Australia at the time believed it could be successfully done'. That is first up over 1600.

Of course recently it has been done with some of the Robbie Laing chasers and stayers - having something like 12 trials before going straight over 3200 plus metres.