My understanding of the guidance in question is that FDA wants the testing process to fairly represent the production variability of a day's production.
So, if your testing is representative to that extent, they probably will accept your explanation.
If on the other hand it appears to them that your testing essentially was a "snapshot" of production, and there is no evidence that it was fully representative of production variability, they might not accept it.
1) Does that mean samples from multiple lots is better than from single lot from the FDA expectation perspective?
2) If FDA prefer samples from multiple lots then is there any guidance about how many lots are appropriate?
3) For example, I have samples from 3 lots (Lot#1, Lot#2, Lot#3), and I have 3 product properties (property#1, property#2,property#3) need to be verified via lab tests. How should I arrange the samples to have better representative of production variability? Which of the below protocol is the best?
Protocol 1:
property#1 (Lot#1, Lot#2, Lot#3)
property#2 (Lot#1, Lot#2, Lot#3)
property#3 (Lot#1, Lot#2, Lot#3)
Protocol 2:
property#1 (Lot#1, Lot#1, Lot#1)
property#2 (Lot#2, Lot#2, Lot#2)
property#3 (Lot#3, Lot#3, Lot#3)
Thanks