It does not require much of imagination that the suggested Distance Spot Ratio of what an electrician needs to have so to aim on a circuit board or electrical panel needs to be 50:1.
The benefits of 50:1 are very specific. a) You can get one very accurate reading by the distance of 70-80cm away ( That is a safe distance regarding high voltage)
b) You can have an accurate reading even up to two meters ( extremely high temperature sources )
c) The diameter of the beam is 16mm = 1.6cm that is almost good enough for aiming circuitry breakers.
In such Infrared thermometers of 50:1 and with one so narrow in diameter beam, those dual pointing lasers is a must have too as aiming assistance.
All the above details they do present clearly the profile which one successfully designed 50:1 Infrared thermometer must have.
What I would describe as even higher in quality Infrared thermometer in the 50:1 Distance Spot Ratio,
it would be the one with even narrower diameter of beam at less than 16mm.