i think you need to set the margin low enough, and the time long enough, for there to be a chance for end game settings to benefit your team in a come back. some people just set stuff really high - whats the point, if losing, to set to 10 points with 2 minutes? you already lost. i think this is the biggest end game mistake. on the if winning side, thats a bit different - i think it should be utilized - but frankly, if you are beating someone already, i can see the logic in not wanting to change things up. but when you are losing - why not? you don't have to do something insane, like press with no IQ. but you should run uptempo at least.
i personally like to defend the 3s a little harder when winning late, figuring that is their most likely chance to come back. so i will usually have a 3-2 if zone or a +2 to +3 if m2m/press on my if winning late. i also play slowdown. if losing late, if i have press iq, i switch to fcp even if i don't run it normally, but minimally i play uptempo, and often sag inside - allowing them to take 3s, figuring if they make them, i was probably screwed anyway - but if they miss, i might now have a shot at coming back.
all this said, my end game settings have saved me very few games, that i've noticed. keep in mind if you switch to them, and they start working (if losing), and you get under the limit, you revert back. this is another reason to set the scoring margin low, which is totally different than how i did this in the beginning.