In this section, I thought I'd share with you some check-in policies that many people use today and aren't out of the box, rather than cover any more examples.
The first check-in policy that's definitely worth looking at is one from Colin Dembovsky. This policy allows you to make sure that code reviews are performed before a check-in is allowed. This can be found in the Visual Studio Gallery at https://visualstudiogallery.msdn.microsoft.com/045730ee-63c0-498e-b972-42b05a2d0857. You can also find the code for it on GitHub, which is extremely useful because, for one, you can see how the policy was written. Furthermore, you can add to it and submit pull requests if you have useful features to add, and these can be found at https://github.com/colindembovsky/ColinsALMCornerCheckinPolicies.