Can you expand a bit on that x1.5 per doubling? Is it that if you double, then rather than doubling the chilli you only increase by 1.5? And if doubling again, and again ... then what?
There's an implicit, logical dead-end to that rule. If we continue to increase the size of the cooking pot at some point there will be no need for any spices at all! It's the cooking equivalent of perpetual motion. It's just not logical.
First of all SS, obviously no one is going to increase the size of a pot as to the point of approaching infinity, and at which the functional incremental spice increase would approach zero.
To expand a bit, yes. This is
a theorized and often utilized practice pertaining to the increased quantity of spicing in relation to the increased volume of primary ingredients in a dish. For each doubling of the primary ingredients there is an applied increase of only 1.5 X the amount of certain spices (as listed above) but certainly including chilli. This may or may not be necessary in the first instance, ie; in going from a single serve to a double serve in the case of BIR style cooking.
So as not to insult anybody's intelligence, I won't do the sums for us. Obviously there is no need to be FOAM (fixated on accurate measurement) and rounding up or down to an appropriate closest measure would be more than acceptable. This is a fairly general cooking practice and I have in the past found several sources confirming the application of the adjustment method. It may be related to the lack of need to use extra ingredients when they are not really required (economy) or it may be related to the actual fact of spice overload of linear scaling, or possibly a combination of both. My reading certainly indicated it the be to prevent over-spicing of dishes. I've posted some links in relation to this theory in other related threads in the past. I guess I could trawl the internet again to see if I can re-find references to this material.