Two main factors impact the lifecycle of a dispute and its resolution time: your initial response time to the dispute, and the issuer's evaluation of challenged disputes.
Following the creation of the dispute, you have a limited amount of time, usually 7-21 days (depending on the card network), to respond to the issuer. The sooner you respond (ie., accept or challenge the dispute), the sooner the dispute will be resolved.
If you do challenge (ie. submit evidence), the issuer then has a limited amount of time to evaluate the evidence and decide the outcome, usually 60–75 days (depending on the card network). The decision is made by the issuer during this period, and Stripe has no impact on the issuer's timeline for this review. Once Stripe receives the issuer's decision, the dispute will automatically be updated to reflect the resolution.
Ultimately, the full lifecycle of a dispute, from initiation to the final decision from the issuer, can take as long as 2-3 months to complete. There are no actions you can take to reliably accelerate this timeline, other than by accepting the dispute in the Dashboard or API to resolve the dispute in the customer's favor.