I have found another side of this, which is that some drivers are so eager on their outlap that they exit the pit in front of drivers, or drive so fast on their outlap that they catch up slower drivers actually on a "hot" lap and then either try to pass or drive so close that it is a distraction.
I would suggest keeping a fair pace on the outlap, not fast enough to catch anyone up, but not so slow as to get in someone's way. If someone catches you up on an outlap then move over. If you are on an outlap you probably shouldn't approach someone you are catching up, but rather back off and get some air between you and the guy in front.
If you are on an outlap and you do catch someone up and they are not on a hot-lap I am sure they will move over for you. If they don't move over they are probably on what for them is a "hot-lap". Please respect that. Also the slower guys want to be able to do their best in qually without being expected to give way to fast guys on outlaps.
One other thing about respect, when you have been lapped. If you are a lap or more down in the race and you catch up someone, you might feel like you want to unlap yourself. I think we should ask ourselves - would unlapping ourself actually make a difference in the race? In other words do we have a real chance of making up a race position?
We should also evaluate whether unlapping or attempting to unlap might affect the race of the person we are trying to unlap ourselves with. If there is little chance of making up a race position then please do not attempt to unlap.
Back off and give the guy in front some space. Don't hang about in their mirrors, don't move up the side and then back off, etc. You will likely cost the guy in front time and prevent him catching up the guy in front of him, and you may cause him to make a mistake. Of course "making" him crash several laps from the end could end his race and gain you position, but it is hardly friendly or gentlemanly racing.
If on the other hand you are are the driver being closed on by someone who has been lapped, and they are clearly faster, and you do not have a realistic chance of catching the guy in front of you, then by all means let the guy behind unlap himself.
Just my opinion.