Three resin lots required for part qualification

[gj.shao]

First, as far as I know, there is a ISO standard which is used as a regulation for sterilization for medical packaging validation. Three resin lots requirement reffed to this requirement.
Second, the reason why chose three lots resin is to simulate the real production situations. In this way, it could identify materials differences risks.

[chrisprocess]

I've run 3 lots of resin many times, but only if customer requires it.
The work-around is justification of a robust processing window. The argument is if you qualify a higher injection speed + higher pack pressure and a lower injection speed with lower pack pressure (among other parameters) you've covered your basis of any lot variability you might encounter