Yes, that’s correct, a single diode. A multiple diode array will not affect the recommendations as the dose is “per point”. You are using a device of high output power (I am assuming it is average power and not peak power, right?)
Generally speaking, you are correct that you are likely to need lower fluence (energy density or dose, if you like) for acute conditions and higher fluence for more chronic conditions.
However, the other factor to consider is the depth of the target tissue. You’ll note in the WALT recommendations that deeper joints (lower spine and hip, for example) require higher fluence. I urge you to use the WALT guidelines as they are, at this time, the best evidence-based recommendations that we have. Cheers, Liisa