Practice does not make it perfect?

[SarathW]

Practice does not make it perfect?
I saw the above statement in a roadside traffic slogan.
In my opinion, this is a wrong statement. What I think is that the practice makes it intense and permanent.
This is important when it comes to Samatha meditation.
What Samatha meditation does is s making intense and permanent your former habits.
For instance, if a thief practices Samatha meditation he can become a world-class bank robber.
So that is why it is important that you have some virtues and should start observing five precepts before you start your Samatha practice.
If you have bad practices prior to Samath meditation you make your bad habits intense and perfect.

What are your thoughts on this?
Do you have any Sutta support to accept or reject my thesis?

[bpallister]

"Nobody wants to work anymore." (at anything)

[wenjaforever]

If a thief wants to become a master be a federal judge