I always walk them if I have an ownership interest in a horse.
This year I've walked 4 tracks. Ellerslie 3 times.
None of those are really necessary. A good heel and a strong thumb can give you a good idea. I focus more on other factors than the "give".
Within the Good 3 to the end of the soft range it doesn't matter what the rating is as all horses should handle it.
Depends on the distance that I'm interested in. I'll walk a whole round if I can and at least the distance of interest.
I'll walk different parts/lanes on the track from the point where horses will make their runs from e.g. wider on the final bend and home straight.
I'll check for consistency across those lanes. Factors I'll focus on are surface evenness I.e. is the surface rough, showing wear and tear, broken and or shifty. Most horses hate it shifty and tend to hold back to protect themselves.
I pass the information onto the trainer or racing manager of the horse I'm interested in.
Once I recall telling the track staff at Ellerslie (2006) of a serious problem in the straight. A four foot deep hole about 15cm in circumference. Shoved a tree branch down it at about 8 am in the morning.
What I have learnt is very very few Trainers or Jockeys walk the track prior to racing. Those that do have an advantage over those that don't.