> assuming equivalent efficiency of conversion

Is there any case where this is remotely even true?! The way advertising budget is spent always has an enormous impact on the outcome.

One competitor spends in print, another on TV. One competitor targets young professionals, another families with kids. One competitor goes to best and most famous agency but buys the cheapest package and fights any decision, another gets a genius kid at the beginning of his career to create a most brilliant TikTok ad. Etc...

> I suggest you look at how advertising works

A valuable advice, try following it sometimes.