The shingles need the right roof beneath them
Shingles rely on a suitable deck and underlayment, correctly placed fasteners and sound details at edges and openings. Starter and ridge components also form part of the system. An upgraded field shingle cannot make a weak base or failed wall joint dependable.
Ventilation needs the attic and roof assembly considered together. Exhaust without appropriate intake is not a complete airflow plan. A separate low-slope porch can also need a different covering instead of simply receiving the same shingles as the main roof.
For a small repair, compatibility with the existing shingles matters first. Dimensions, exposure and the ability to lift adjoining courses affect the repair. A new color may remain visible even where the work is sound.