60’ for 5 canter strides (or 4… or 6…) pole to pole
IMO, it’s not the best exercise to simulate a jump to jump experience because ground pole to ground pole rides differently than fence to fence.
If you get in deep to a fence you usually have to make up some distance to get out correctly (move up) and when you get in long, chances are you will have to settle to get out correctly.
But it just about the opposite for a pole to pole experience - if your last stride before the pole is very close to that pole (like a deep distance) then you will eat up a lot more ground in your first stride in your 60 feet and generally have to wait to make the 5 work. But if your last stride before the first pole is farther away (long) then the horse lands closer to that first pole and you have more distance to make up. It’s a good exercise and it teaches you awareness of where you are, but you need to understand that it is a bit counter intuitive to how you would ride the line if the same thing came up with jumps involved.
Maybe a better exercise is a pole to X to pole - 60’ before and after. Trying to create the same amount of strides going in and going away will humble most of us pretty quickly (but teach us a lot about the quality of canter needed to jump a good fence, regardless of height)
Also, it’s not a universal 6’0 takeoff/landing arc, the takeoff/landing arc is wholly contingent on the quality of stride approaching a fence. If you float their teeth off coming into a line and create a 9’0 stride, you will not have a 6’0 takeoff, more like a 4’0 takeoff.