The hittaut courses I did in Sweden last year used L-shaped aluminum stakes with stickers, or, in urban areas, laminated "cards".
https://mora.se/wp-content/uploads/Peka-pa%CC%8A-s...https://www.dryden.se/wp-content/uploads/2022/05/h...No punches, just numbers (to identify the location) with letter codes (recorded to prove you visited). These are semi-permanent, out for ~6 months or so.
ROC uses the carsonite posts for permanent courses and 4x4" laminated cards with a hole punched in the corner for a ziptie for semi-permanent courses. I have had the hole break over the course of a winter, but the cards themselves are reasonably sturdy for a seasonal course. They should be hung with a streamer because the cards are hard to spot if you come at them edge-on.