Maximum distance for kneelers and standers is 45 yds, and they have to be a 40mm or 45mm kill. 6 lanes in total, so you can have 3 kneelers and 2 standing lanes, or vice versa, or i suppose 1 of one, and 4 of the other although i've never seen this.
There is guidance on what the combined length of the positional lanes should be, but i don't know what that is.
Smallest kill allowed is 25mm, at no further than 35yds. These can only be used on non positional lanes. 10% course maximum (i believe)
Think anston's average was 47yds, but bear in mind that a course can be long and have a couple of 8's or 10's to bring it down somewhat.
I think lanes should be have something in the 40's and 50's but also something closer now and then.... and a lot of varying direction and heights and exposure to the wind, as well as a couple of light and dark targets to add to the flavour.
It's a like cooking... you can say you need x teaspoonfuls of whatever in there, but really it should be flavoured to taste. Dont forget that still or harsh conditions will see the target length shift somewhat.
If you want to practice for longer stuff, then wind exposure is something to play with... doesn't need to be all fully exposed, you can trip people up with sheltering as well... and a lane or two with awkward ranges, like 48 or 53, to test rangefinding as well can help focus people's rangefinding skills.
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