Rocket recovery and reuse

For every pound you must invest in the heat shield for the recoverable rocket's orbital* stage you will lose one pound of payload. Does it make sense then to recover simple tankage? Perhaps one should only recover the engines, pumps, and avionics. I.e., something like** ULA's "SMART" but applied to the upper stage***.

* typically second stage 

** may or may not use inflatable heat shield

*** or think drop tanks