Is it permissible to pray some of the regular Sunnah prayers, such as the two Rak'ahs of Fajr, and omit the rest, while being diligent in performing the obligatory prayers?

A Muslim should be keen on performing supererogatory prayers (Nawafil), especially the regular Sunnah prayers (Sunan Rawatib), as they are among the reasons for Allah's love for His servant, as stated in the Hadith Qudsi: "My servant continues to draw near to Me with supererogatory deeds until I love him." Adhering to the regular Sunnah prayers is highly emphasized, and whoever abandons them does not commit a sin, but he deprives himself of a great good. Some scholars have been strict regarding their abandonment, which indicates their great importance and the significance of observing them.