Not too much of an issue. The intermediate band is pretty small in a TH350 and TH400, slightly bigger in a later 4L80E. We use the late 4L80E band for any engine braking 80E or 400.
We also do some spragless stuff on the TH400 for extreme offroad combos.
For 2-3 times a year, don't sweat it. You may tune it for max line pressure at 0% throttle while competing and if/when it needs rebuild be sure to put the late band in it.