[Solution] Copying over only columns that you are interested in (rather than all columns)
Figured out a way to overcome the problem where all columns get transferred over from source to destination. This isn't a problem when the function of the destination sheet isn't critical/widely used, but for certain bulky sheets (large columns/many rows) it becomes important to be efficient as you can only have 500,000 cells in a sheet.
Doing this requires 3 sheets.
1: Source Sheet
2: Row Indexer Sheet
3: Destination Sheet
In the Source sheet, set up an auto-number column that will count how many rows there are (Always adds +1)
In the Row Indexer Sheet, set up an auto-number column and max out the sheet (for scalability). You can easily get ~15,000 auto-numbered rows like this.
In the Row Indexer Sheet, use an INDEX(MATCH formula to Index only the columns you are interested in copying over to the Destination Sheet. Match the Auto-Number in the Indexer Sheet to the Auto-Number in the Source Sheet.
Set up any type of automation for copy over to your destination that you prefer (Rows added/Changed for instant; Daily at a certain hour for a cron-like copy over).
Voila, you can now easily copy over a custom number of columns without any problems.
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