Grids in Canvas using free allowance

Hi All,

Following on from this question:
Checklist within a row? - Ask the Community - Coda Maker Community

The best solution for us was a grid in a canvas column.

But, adding just 1 or two rows with a grid in seems to MASSIVELY eat a document’s free allowance e.g. current doc size with 200+ rows in the table is ~26%. Adding a single row with a 22 line grid in takes that to 57% and adding another row with a grid in takes it to 98%!

Is this a bug in the calculation, or is it genuinely using more space for some technical reason? If the latter, is there a more efficient way to do this?