I think you may be missing my point. I am advocating putting the finditem() and figuring out the mapping to the Month Name in system module rather than doing the formula in the module with both lists (time as well as month offset). Yes, you still need the lookup in the Time by Month Offset module, but not the mapping of Time to Month Names. If you look at my last picture above, it is resolving to the correct answer (same as yours), but in doing the mapping of the Time to Month Names in a system module, that formula is getting kicked off fewer times, especially when you add more years to the model, which makes the process perform much better.
Additionally, by placing the mapping in a system module, other model builders may need the same mapping which can be easily found in a system module and not hidden away in a Calculation module, thus they will not have to recreate the same functionality.
Hope this helps,
Rob
Yes, the "system" module is just a term we use but it could also be Structure. It is not inherit to they system at all, but helps with mapping, filtering, master/meta data of lists. The one above is based off of Time, where you can do the mapping to the Month Names as well as filter out all quarters or years. Another example could be on the base member of a Product Hierarchy where you are figuring out what the parents are (P3, P2, P1). If you have these in one module, all module builders will know where to get the data instead of recreating the wheel in their own modules.
Again, the main benefits are:
Hope this helps,
Rob