Readers interested in the VTI-TLT-SHY model and the performance of other benchmarks will find this article of interest.
When comparing portfolio performance to benchmarks, I use VTSMX as one standard. To align or fairly compare portfolio performance with an appropriate benchmark, I prefer the ITA Index as it is a customized benchmark designed for the different Strategic Asset Allocation plans for each portfolio. The ITA Index is a benchmark users of the TLH Spreadsheet construct within the software program.
Regardless, check out the above article for more information on benchmarks and some of the models used to manage portfolios.