I find hourly backups to be very intrusive. If I did decide to do hourly backups, I might choose to back up a smaller subset of files (e.g. vs. the entire filesystem) so the backups occur very quickly. Otherwise, I'd just set the system to back up when I'm not using the system. My production machine backs up once a day at 5:30.
Feel free to experiment with the frequency of the backup to see what works best for you. I've decided that the risk of failure on any given day is low enough that I'd rather not have it interfere with my productivity. If an hourly backup were to cause me a minute or two of productivity loss per run (via distraction, having to wait, or generally slowing me down), that would start to add up quickly. Eventually it would outweigh the four hours of work I might lose if one day my drive failed at noon.