Correct, these are independently prepared and optimized.
So what? The query is not even using bind variables in the first place and fairly simple , too. You shouldn't loose too much time due to re-parsed statements here.
For generally re-usable statements the ABAP layer provides the means to handle this very efficiently.
However, for SAP BW the typical application is not to have many complex statements that are exactly the same run over and over again.
Could you optimize the parse time for your example? Sure.
Would the improvement be large enough to rectify taking out code that highly improves the options to analyse more complex scenarios efficiently? Probably not.
Would your improvement be worth while a separate line of code in the data manager? Probably not again.