In a recent reply to a post in Support, I set out a step-by-step process to create a table intended to drive an Airtable Chart Block bargraph, based upon the multi-record calculation routines I described earlier.
In this case, the routines are not used to access values across multiple records; instead, they drive the population of a third table, allowing for the date and value from the previous X number of entries to be charted. At each new record from the [Main] table is added, the Xth value is dropped, the remaining values are moved up one position each, and the current day and value displayed as the most recent.
Aside from linking each newly added [Main] record to [Calc] — a task that adds two mouseclicks to the record creation process and that may easily be automated using Zapier or equivalent middleware — once implemented, the routine should require no additional maintenance for nearly twenty years.
Again, the reply describing the steps needed to implement the chart is here; the initial post describing the core routines here; and a demonstration base, including Chart Block, built according to the instructions, here.