Summary covers stretches of time efficiently; scene slows attention through specific actions, perceptions, and dialogue. Choose the event whose significance deserves space. More words do not automatically create tension unless their details serve the moment.
Worked example
'For weeks she practiced' compresses time. Describing one hesitant breath before the audition expands a critical second. Both techniques can coexist in the same narrative.
At the Workshop Door
'For three months, Amari rebuilt the broken instrument after school. On presentation day, Amari crossed the hall, opened the workshop door, and showed the repaired instrument to its owner. The owner recognized it at once.' The writer wants to emphasize the uncertainty just before the owner sees the repair.