The wedding Tithis and Muhurtas are also referred as Vivaha Lagna which is largely responsible for subh, sadbhava and sheel and also materialization of Trivarga Sadhana (Dharma , Artha and Kama). The quality of progeny and their behavior is also subjective to Vivaha Muhurtas.
Usually parents get a horoscope and they refer to a Pandit or if they are Astro savvy, they use software to know, if the Nakshatra are matching and then they declare yes to marriage whether would be good or bad as the case may be.
A PANDIT may at the most see additionally the chart for a possible ‘manglik kuja dosha’ and reject or accept a horoscope for Yejamana, once accepted, then family bursts into happiness and a Muhurta is chosen as per convenience, oh my daughter has no leave, uncle cannot come in may, my best friend has to attend two more weddings on that day, all the particulars have to be examined, groom wants to leave for the offshore assignment, choultry is not available. PANDITji then gives a convenient date. Least people are bothered about importance of Muhurtas and whether it matches bride and groom for a long happy journey.