That’s fair, we’ve just had very different experiences with 3 yr olds obviously. Mine are the same at 5 as they were at 3, they just have more training.
Me, i can leave my gelding alone for 2-3 weeks, bring him in, tack him up, and put my beginner cousin on his back for a 20-minute walk/trot lesson on the lunge line. He’s THAT quiet. Every time - all the time. He has had maybe 60 rides on him total since late last fall. He is what he is, he has been this way since he was born, he’s just sensible like that. So was my last youngster, and the one before that. Safe, safe, safe. Day in, and day out.
Being well trained is a different story. Sure if you ask him to canter a 10 m circle, go down the diagonal and do a flying change, he won’t be able to. But you know what? He will try his best.
Temperament/disposition/heart doesn’t change, or at least very, very little - if they’re bombproof superstars at 3, it ain’t gonna change.
But anyways, so sorry for derailing your thread, carry on!! I think Arab/WB crosses are wonderful too!