You can do either. Once of the nicer thing about the DVR is the integrated guide. You find what you want, click on it and it can record one or all episodes. The downside to that is that you are subject to the scheduling quirks mentioned above. Then when you go back to watch what you've recorded, you just run down your list of recorded shows and watch it.
If you have a bunch of manually recorded shows on your DVR, it can be difficult to know what's what as it is just listed as "Manual Recording". The time stamp of when it was recorded may clue you in to what it is, but if you have a big DVR loaded with stuff, it can make things hard to find.
Live events are usually best to do manually because they often run over. I don't know if they do this up your way, but many US shows are scheduled to run in a timeslot (say, 8:00 to 9:00), then the network intentionally lets the show run a minute or two long. You end up missing the last few minutes since the guide "thinks" the show ended on time. OTOH, if the program guide is actually correct (8:00 to 9:02), your DVR will possibly miss the next show you want to record at 9:00 due to the overlap.
The good news is that many TV shows are also available on web sites like hulu or the networks' web site (or via other means
). So if your DVR gets screwy, you can always catch your show on line.