I find that if you are taking a smaller serving size (1g-2.5g) that you have far more flexibility with using the same "strain". I dont know if everyone experiences this, but I find that with larger serving sizes you have to wait 1-3 weeks between each serving of a specific strain to get the full effects.
Regarding your question on new batches, you can pretty much treat each batch as an entirely new strain. I would estimate that around 99% of the time a vendor receives a new batch it is NOT just a later harvest from the same exact group of trees. The way that most of the industry is set up just doesn't support the possibility. What some of the better US vendors will do is order the same "strain" from the same Indonesian source, but what that means can vary completely depending on the Indonesian supplier. A minority of the better Indonesian suppliers will try to keep integrity with their strains in the fact that "Bali A" will always be an indoor dried leaf from "Source A".
However, "Source A" can mean many things.
1. Source A might be a leaf broker who buys leaf from all over the area - basically anyone who brings them leaf to buy.
2. Source A could be a solo harvester that goes out alone or with a group and harvests wild trees from all over.
3. Source A could be a specific village/town where there is a collective industry of growing/harvesting and crushing.
4. Source A could be a collection of local farmers on a private social media platform.
OR
5. Source A can be a single plantation.
Option 5 is what would give you your best bet at having some-what of consistency between each batch. The good news is if you ask an Indonesian supplier, 100% of them will reassure you that they only use their own leaves or use a very specific private farmer who just so happens to have the highest quality of mature trees.
With that said - it certainly possible to obtain leaves from the same exact source. It's just far less common as there is every incentive not to do so (it really restricts you with product availability, cost, etc...).
However, if you are able to lock in leaves from a single source, you still have to contend with the fact that tree composition can vary wildly on the very same plot of land (depending on the tree's age, physical location, human manipulations, etc....).
As an example - a specific line of our batches come from the same source of wild trees. However, there are quite a few trees within this source and there are great compositional variances in the different sections due to the various environmental influences. For starters, trees that are located closer to the Hulu river experience different levels of moisture and have a much different soil composition than those that are further on the interior. Additionally, some of the trees are more spread out versus those that are tightly grooved resulting in different exposures to sun and wind.
To further complicate things, significant differences can occur within the very same cluster/section of trees as a result of specific pre-harvest manipulations (applied nutrients, frequency of harvest, etc...).
Take a quick look at the two pictures below. Both of these pictures show a great diversity of trees from a single source (this is private land that has both a plantation and wild trees). As you can imagine, the leaves from trees in each of these sections may produce a wildly different alkaloid profile (some more noticeable than others). Unless the producer is being very purposeful and diligent with what trees each batch leaves come from, your next order of "Bali A" could be nothing like the last one.
And to add the cherry on top - none of this takes into account other environmental factors that change with time (such as temperature, rainfall, etc...) and the entire post-harvest production (drying technique, etc..)! I can tell you from personal experience that it is very difficult to "re-create" the same batch months later, but with the right conditions (some of those conditions are out of your control), you can get it pretty close.
Wow - I really went off on a tangent there haha. I love talking about all things kratom, sometimes I just can't help myself.