To me a similar thing is seen with Anadrol as with Dianabol: as a component of a stack or in combination with a sufficient amount of injectables, or oxandrolone, 50 mg/day can be very effective and is really all that's needed. But if the amount of injectables or oxandrolone is insufficient, then 50 mg/day may seem not too effective.
With Anadrol there's more tendency to try to compensate, if the other item or items are insufficient, by jacking up Anadrol, to 100-150 or even 300 mg/day. This works better with Anadrol than with Dianabol, but still is nowhere near as effective as combining it suitably, in which case the 50 mg/day is fine. I would divide the dosage though, if you are not already.