One of the biggest reasons that users churn or bounce is because of confusion (having to make a decision without sufficient information) or anxiety (fear of the unknown), so avoid this for your product tours.
Ensure you set expectations early on, for what a user should expect from your tour -- both the value, but also the cost. The latter can be in the form of the expected time, or the number of steps.
You can use the 'Progress indicator' to automatically show the number of steps in a tour, available both as breadcrumbs or as "Step X of Y" format.
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