Dual hps/mh ?

I have a question about a 250 watt hps system....i heard that it can grow 2-3 plants very well...but how well will it do a single plant...given the right conditions....

I suppose you kinda answered your own question. if a 250w hps will allos 2/3 plants to thrive 1 plant should be happy as heck.

i was looking for more of a time frame.....would it be done faster