@Eric The Viking yes strobing is the flashing of the light, the danger being that flashing at certain frequencies can cause a rotating machine to appear as if it's not moving.
Output from a fitting is measured in Lumens.
Illumination òf a given area is, in Europe, measured in Lux. As you correctly say, effective lighting design is the correct fitting selection and location of fittings to provide effective illumination. In a workshop this will include good uniformity.
Power Factor in quality LED lighting is generally better than 0.95. Power Factor is seldom of significance in energy calculations in lighting where LED is used.
The efficacy of lighting is the critical issue when evaluating a Lighting fitting. This is expressed in Lumens per Watt.
The efficacy of an installation is expressed as Watts/100 Lux/Meter Square. Yet as most here won't be able to know what light level they have in Lux, this is all academic.
So it's best they just look for light fittings with a good Lumens/Watt. Good fittings today will give about 120 Lumens/Watt.
It wasn't my intention, when writing my post, when in bed this morning, to write a full comprehensive guide on lighting design. I also didn't expect to have to cross swords with anyone here.
Maybe you'd like to explain why cheap LED fittings do flash, while Philips Fortimo boards and Xitanum drivers, or the Tridonc or Cree circuits which I use in fittings we design and manufacture, don't?
Moving on, what folk may like to gain from all this is :
If you have fairly new fluorescent lighting (less than 10 years), you will probably gain more benefit by fitting new lamps, than rushing out and buying LED. LED is more energy efficient, but for most people it's not always best to replace. Especially if you're only working in there 10hrs a week. What matters is how long it will take for the energy savings to outweigh the installation cost.
All light sources lose output over time. So, if your old fluorescent lamps are dark at the ends, replace those at >£5 a time, rather than £50 for a half descent LED fitting.
Also, to get the most from any lighting system, where possible, paint your walls and ceiling white. This will add significantly to the light levels: which is what matters.
P.S.
Why did I ever bother trying to help people? In future I'll just shut up.