Efficiency of O–C diagrams as diagnostic tools for long-term period variations - I. Wind-driven mass loss and magnetic brakingN. Nanouris, A. Kalimeris, E. Antonopoulou and H. Rovithis-LivaniouA&A, 535 (2011) A126DOI: https://doi.org/10.1051/0004-6361/201116707