Google Sheets natively controls how the functions recalculate according to different behaviours (modifying cells, opening the spreadsheet, …). This is why you wasaw your functions recalculating and your data loading.
But fear not!
- To avoid that IMPORTFROMWEB fetches the data source constantly, imported data are cached 24 hours by default (and up to 4 weeks). See on this page how to manage the cache.
Therefore, whenever IMPORTFROMWEB recalculates, the content is retrieved from the cache and it is not counted as new requests. - You may add the hard_paste option as a 3d argument of the IMPORTFROMWEB function; it pastes the collected data as values directly into your spreadsheet, so you’ll never get a “loading…” again for an URL already fetched!