The kind of changes that might throw you into learning mode are as follows:

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Google tracks 40,000 different data points with every search auction conducted. They then aggregate the data into audiences to create similar visitor profiles and test how those different visitor profiles perform for you. Once Google knows how the visitor profiles work for you, they come out of learning mode.


New strategy – The bid strategy was recently created or reactivated
Settings change – A setting for the bid strategy was changed


Conversion action settings – You’ve added or removed a conversion advertising data action related to one of your bid strategies, changed the “Include in Conversions” setting, or changed your conversions “Count” setting
Composition change – Campaigns, ad groups, or keywords have been added to or removed from the bid strategy
Google says that budget changes no longer put you into learning mode but, to be on the safe side, it’s better to do small frequent changes in budget rather than larger, ad-hoc ones.