Does Reducing Trip Duration Help After Spain Schengen Refusal?

My first Spain Schengen visa application (15-day trip) was refused under:
“Purpose and conditions of intended stay were not reliable.”

Now I’m reapplying and considering reducing the trip duration to maybe 7–8 days so the itinerary looks more realistic for a first-time Schengen applicant.

My question:
Do Spanish consulates compare the new application closely with the previous refused one?

For example, if I previously applied for 15 days and now apply for 7–8 days, would that create suspicion/inconsistency? Or can a shorter trip actually help?

Would appreciate insights from people who reapplied after refusal.