By trusting a source to label batches accurately, you're making yourself vulnerable to batch obfuscation - let me give you just a few examples:
You've sent batch 1 for blindtesting and the result was great? If you're not going to check me periodically, I'm going to put batch 1 on all new batches of that product until the mfg.date of the original batch is perceived to be too old.
Batch 1 blindtested horribly? I'm going to make a better batch 2, wait for that to blindtest well to afterwards mix in the old batch 1 products but with batch 2 labels if you're not going to check me until the 'next' batch.
Batch 1 blindtested well but five years in I still have leftover batch 1 vials? Going to give those an extended lifespan by putting the batch 2 label on.
You can mix and match these and many others of course while reminding customers that indeed this batch has already be blindtested! Isn't that reassuring.
Batch numbers offer a sense of comfort to the customer, but bware that this potentially false comfort can be used against you. Disregarding batch numbers in favour of periodic blind testing is the superior option for customers. Don't forget that every good source will reimburse you in full (usually via store credit) for the cost of blind testing, though not all sources doing this are necessarily good ones.
A sharp minded Meso that holds sources accountable aggressively is a meager meal for scammers, but fluffy sheep Meso is a big fat feast due to the absence of protection via rules/shepherd dogs.