Depends but it is very beneficial!! I would suggest only doing with experience riding horses, not only yours, because IEA is all about showing off your ability to ride and mold to each horse andshwi off your equitation on horses youv never ridden before!! Overall I think it's very fun and you don't need to have show experience for IEA!
It depends on how much experience you have with horses in general, not necessarily show experience. I LOVE IEA, but I’m glad I waited to do it till after I was confidant in riding any horse at any level, and also having show experience under my belt. I would also talk with your trainer and/or the IEA instructor of the team you may compete on. It’s really your decision to make.
We are hosting IEA at our barn this year. It can be very beneficial but it really depends on the barn running it and how well they do it. Schooling shows are often just as good without requiring a membership fee.