Good afternoon Jdb523,
It's true that there is a limit concerning manually set record times. However this limit does not apply when scheduling a recording through the guide.
For instance, if you program the US. Open to record and it is 7 hours long it should give you no trouble and record the entire program. However, if you try to manually adjust that time frame (such as starting the recording 15 minutes ahead of the scheduled start time) it will not allow you to record.
We are looking to adjust this particular setting and if you have any feedback you'd like to share, please post it on our Share Ideas Forum
-Adam_VZ