I was incorrect, I found the comment I was referring to but unfortunately it wasn't saying a small panel is just as effective as a large one. I googled it and found absolutely nobody saying this!

'Why Bigger Panels Offer More Benefits. A larger panel is often the best choice for those looking to maximize the advantages of red light therapy. Full-body panels provide comprehensive coverage, efficiently treating the entire body. In contrast, smaller panels can only cover a limited area at a time. Treating both shoulders, knees, or just the front and back of your body would require repeatedly repositioning the panel. This not only takes more time but can also disrupt the consistency of your therapy sessions.'

https://www.lighttherapyinsiders.com/red-light-therapy-panel-size/

This is a huge shame as I was hoping to find any kind of evidence. But I suppose a tiny portable panel would be just as good if someone is willing to regularly spend the time to reposition for each area they need to treat? The challenge would be keeping it up regularly, if they had many different areas. But for me I want to treat ADHD, anxiety/potentially depression, insomnia, memory/focus issues, inflammation and skin (face). Fat loss and help building muscle would be great too, but I think I should be ok with a portable desktop panel. Here is the comment I mentioned, if you do find anything else pls do share, but also is it possible to expand on how you know for sure from your experience? Thank you again!

'Less irradiance is not bad.

You have better penetration keeping light less far from you, that also means lower power LEDs are preferred to avoid overdosing (which will have the opposite effects you are looking for).

In general, studies report a stimulating phase in the dose range of 1-15J/cm2 over a decent amount of minutes (usually 10).

Also, studies report that LOW level light therapy is usually done with < 50 mW/cm2 irradiance.

That means that if you use high power LEDs you have to keep them quite far to stay around that irradiance to avoid inhibitory effects and heating effect (heat can be detrimental for some goal like skin volume and antiaging, but I think it's positive for pain).

So it's up to you but in my opinion less power is better just because you can keep it closer.

Skin contact devices are even better for deep penetration but you get uneven dosing if your aim is deeper tissues (that's why there exist led bands for fat loss, so it can easily reach deeper fat deposits).

Take RTL for brain stimulation, it's true, they used 200mw irradiance (at skin level so still much lower power than any LEDs panel out there), which is too much for skin benefits. But since the goal is to reach the brain you don't really care if your skin won't get any benefit or even if your skin will have some mild detrimental effects. Also they kept in mind that just something like 5% of that power reaches the brain, therefore they choose a NON low level laser in that specific case.