According to Frequence, combining media products (an omnichannel approach) leads to much higher conversion rates (in some cases up to 3x) for advertisers compared to running a single media product at a time, particularly for local ads. The right media mix also results in cheaper conversions, in some cases reducing the cost per conversion by 50%. There are differences in conversion rates by industry, but all industries see a lift with an omnichannel approach to media buys.

More here: https://martechseries.com/sales-marketing/programmatic-buying/omnichannel-ad-campaigns-produce-better-results-than-single-channel-executions-for-local-advertisers-according-to-new-report-from-frequence/