Interesting! I ride right foot forward but as I’ve broken that ankle I thought I’d work on getting comfortable with left foot forwards so I can switch (once I’m allowed back on the bike!)
I also ride horses and when they’re green they always canter on one lead and you have to teach them to do the other – as with MTBing it doesn’t matter in a straight line but the horse is much more balanced on the correct lead in a corner (although you also practise counter canter so it’s not completely hopeless when you get it the wrong way round). If you watch show jumping you’ll see that they constantly change lead, sometimes with a flying change (where the horse rearranges its legs during the moment of suspension midstride) or they’ll take off for a jump on one lead and land on the other.