I appreciate the replies. Zooming-In isn't so I can drag the I / O points around, it's just to get oriented in terms of the time before and after that point.. Take a 10min clip with only :20 selected, it's hard to see how far forward or behind the cut point you've set if you are trying to just add in a slight bit of dialog, etc... sure you can scrub with the scroll wheel, etc... and keep playing the spot over again, I tend to get a better sense if I can visually see where the CTI is moving. When I find the new spot, I hit I or O to set that updated point... good for fine editing.
Ah well...