  Current planet formation theories rely on initially compact orbital
configurations undergoing a (possibly extended) phase of giant impacts
following the dispersal of the dissipative protoplanetary disk. The orbital
architectures of observed mature exoplanet systems have likely been strongly
sculpted by chaotic dynamics, instabilities, and giant impacts. One possible
signature of systems continually reshaped by instabilities and mergers is their
dynamical packing. Early Kepler data showed that many multi-planet systems are
maximally packed - placing an additional planet between an observed pair would
make the system unstable. However, this result relied on placing the inserted
planet in the most optimistic configuration for stability (e.g., circular
orbits). While this would be appropriate in an ordered and dissipative picture
of planet formation (i.e. planets dampen into their most stable
configurations), we argue that this best-case scenario for stability is rarely
realized due to the strongly chaotic nature of planet formation. Consequently,
the degree of dynamical packing in multi-planet systems under a realistic
formation model is likely significantly higher than previously realized. We
examine the full Kepler multi planet sample through this new lens, showing that
~60-95% of Kepler multi-planet systems are strongly packed and that dynamical
packing increases with multiplicity. This may be a signature of dynamical
sculpting or of undetected planets, showing that dynamical packing is an
important metric that can be incorporated into planet formation modelling or
when searching for unseen planets.
