Like TT said, none of this matters if Tom isn't willing to have years where he blows past the cap. If Tom's absolute ceiling for payroll is something like $15-20M past the cap, the difference between a 20% penalty and a 50% penalty is like $5M. And Jed hates signing QO free agents as is so that's not a major consideration either.
There was a poison pill in the last CBA where 3rd time offenders lost out on revenue (it was something tied to the Oakland A's revenue sharing), but to this point as far as we know it's just those tax rates nowadays.