Depends on the situation. Runners smarts, speed, game situation, etc. I was always aggressive....figuring that IF has to field it cleanly, make a good throw and the catcher has to put the tag on. I should say that I only coached thru 16U, not 17U and up. Also depended on who was on 3rd. My son was a good slider and knew enough to slide wide and get his hand in. Other kids would slide directly at the plate no matter the situation. I like to see my son's college team being aggressive with runner on 3rd (but not to the point of stupidity lol) They struggled a little to score runs last season, so making an out an home always was a bigger deal than it might be with other teams.