Omega says that this allows the LdP to take more accurate measurements during the 15 days of chronometer testing according to the ISO 3159 standard. https://www.orologidilusso.it.com/Collezione/iwc/ This standard outlines the positions, https://www.popuhren.de.com/produkt-Sammlungen/panerai/ temperatures, and conditions a watch must undergo to meet chronometer standards according to ISO. The 15-day testing period is specifically for wristwatches (if you care, carriage clocks get https://www.fabriekhorloges.cz/best-category/vacheron-constantin/ measured over 19 days and quartz watches over 13 days).