The answer, as Florida found out, is no. It costs far more money to pay for all of the drug tests than it saves by kicking users off of welfare.
Well, that and the fact that it is a politician steering .gov funds to companies that contributed to his/her campaign.
As a money saving plan, this one is sheer idiocy.
A better plan would be to legalize cannabis, regulate and tax it like tobacco. That saves us huge amounts of money from the criminal justice system, shuts down the black market and associated crime and even generates revenue through the tax on the cannabis as well as the taxes paid by workers who otherwise would have been in prison costing us $40,000/yr to support and all of this for a drug that isn't chemically addictive and is less debilitating than alcohol when intoxicated.
Personally, I still won't use it or other drugs. There are wonders enough in the universe without dulling one's senses.