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Given the benefit of focusing on penetration, and that advertising shows diminishing returns as frequency grows, you should generally aim to maximise campaign reach. In fact, reach and frequency are closely related.  This means that if you want to achieve very high reach, you’ll inevitably end up with lots of people seeing your ad a wasteful number of times. 

'High frequency is the tax you have to pay I order to achieve comprehensive reach’ (Dale W. Harrison). Like any tax, do what you can to avoid paying more than you have to. To minimise the tax, aim to use multiple channels to increase reach rather than putting all you spend in one channel.

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