Is it really? For imaging equipment it can be sometimes, up to a certain point. For gamma cameras, more heads is better because it shortens the acquisition time. Once you get up to 4 heads though, you start to run into practical limits like weight and head size.
There's a new CT scanner in the house from a big German company that starts with an S. It's not just any ordinary CT scanner though. This one has two x-ray tubes instead of the usual one. I missed the installation phase when the covers were off so I didn't get to peek inside the gantry to see how things were arranged. I would imagine that the tubes are arranged on opposite sides and slightly offset along the Z-axis (going into the gantry) so that instead of covering the regular 20-30 mm beam width, this thing probably covers twice that. That means it can acquire twice the data in a single rotation. It also means potentially twice the radiation dose to the patient.
Apparently a dual tube scanner proved useful enough to turn it into a commercial product. I'll get my hands on it today and put it through a few checks. It will be interesting to see how this thing performs. Once the apps people come through and set up some clinical techniques, it will be very interesting to see how the radiation dose compares to our other scanners. The timing is pretty good, since it's time for the annual survey on the CT scanners anyway. I'll be able to get some current data for the dose comparisons.