Looking at some LT3042+transistor power supply on ebay, the transistor being used is D45VH10, and is specified that the max current output is 1A, is there a reason it can't do more?
Probably to keep the transistor alive.
Factors such as input voltage and output voltage, heat sinking, output current, ambient temperature come into play.
Factors such as input voltage and output voltage, heat sinking, output current, ambient temperature come into play.