The cost of preparing the statement, while non-zero, usually is effectively zero when compared with the cost of executing the statement.

Additionally, there is the cost of maintaining the code. One prepare() call has traditionally been used for preparing one statement. Breaking that could cause issues when someone else tries to maintain your code.

As always, I would suggest trying it out and seeing what happens. The results might surprise us all.

Caveat - as with every non-vanilla usage of DBI, this is going to be dependent on the specific RDBMS you're going to be using. You have been warned.