Stu, think of it as a relationship you’ve started. Some times it comes easy and all the lines of communications open at once and other times you need to make more of an effort. It really is about good communications, being confident in your buddies skills, relaxing in that confidence without becoming complacent and enjoying the time together. Those you want to skip are those that draw you into making bad snap decisions or are so interested in their own agenda they can’t be attentive to your needs. For example a good buddy that you’ve dived with often could try to entice you into a profile your not ready for or knowing your limits help expand your skills without taking you into a situation beyond control. You as a good buddy must communicate your apprehension of a profile that may make you nervous or is beyond your abilities even if it is just a temporary limitation. All good relationships require good communications and self assessments. Like any other just walk away politely if you feel more effort isn’t worth the investment. Just do it before or after the dive.