Ive tried quite a few brands and the only brand that I have tried that seems to work is Source naturals and I take 10mg a day.
Do you let it dissolve between cheek and gum or swallow it? Assuming the product is even good, if you swallow it you only get about 1% so 1% or 2500mcg is 25mcg. Thats less than the daily requirement and your taking it once a week.