  Core collapse initial conditions are a bottleneck in understanding the
explosion mechanism(s) of massive stars. Stellar evolution codes struggle after
carbon burning, and either stop or adopt numerical simplifications missing
crucial physics. The use of small nuclear reaction networks (NRN) that account
for energy production but bypass weak reactions is typical, but insufficient to
study the dynamics of the collapse. We advise against the use of progenitors
computed with small NRN in expensive multi-dimensional simulations of core
collapse, bounce, (jet formation), and explosion.
