Yeah, 3-ish isn't a bad idea for probably 10-15 degrees. If the tank is somewhere cold (like a basement) or you have warm-water fish (like discus) you'll want to increase the wattage.
But I agree with splitting it up between a couple heaters if you don't mind the clutter. All heaters will bust, and unfortunately, all too often, they bust in an "on" kind of way. That said, there are better heaters and worse heaters. Consensus is just go with a Jager.