My rule of thumb for asking for a ruling is this.
1. You might not know the exact rule but have an idea of what the rule is and how it is worded
2. Know the reason you are asking for relief
3. If I am ever to ask my playing partners for relief I think to my self “This the final hole of a matchplay championship, the score is all even, so should I ask my opponent for relief would it be reasonable to assume that he would grant it.”
If you dont think any one would grant relief in circumstance 3. then dont waste time, dont try and stretch the rules. Its just rub of the green, or in some cases its rub of the pencil at the 19th hole