In which scenario would a client most likely require custom rules for revenue recognition in Stripe?

The scenario where a client would most likely require custom rules for revenue recognition in Stripe is when handling varied taxation based on product types. Different products can have distinct taxation requirements, which can significantly impact revenue recognition. For example, certain services or goods may be taxed at different rates based on state or country regulations, and revenue needs to be recognized in compliance with these tax laws.

In this case, clients need to customize their revenue recognition rules to match the tax implications associated with each product type thus ensuring accurate reporting and compliance. This customization would involve defining specific rules within the payment processing and accounting setup in Stripe, tailored to each product's tax category.

The other scenarios, such as offering promotional discounts or tracking payments across subscriptions, typically do not necessitate alterations in how revenue is recognized but rather involve standard transactional processing. Managing customer relationships effectively relates more to CRM functionalities rather than revenue recognition specifics.