For example, my playing partner is 30 feet short of the hole and has a straight uphill putt. I am hole high and have a 15 foot putt with a lot of break. I'll go ahead and read my putt and replace my ball with it aligned the way I want it. I do this while my playing partner is doing the same for his putt.
Many times, my playing partner will see what I'm doing and ask if it's his turn or mine. I reply saying he's out and I'm just getting ready for when it's my turn.
Is this bad etiquette? I don't want to distract someone else while they are preparing to putt. At the same time, I feel most golfers are the worst at playing ready golf when they are on the green. I would never do this if my ball was anywhere near another's line or when they are actually over the ball and ready to putt.