Is it sufficient to perform istikharah by supplicating after finishing the obligatory or supererogatory prayer, or is it necessary to pray two rak'ahs specifically for istikharah?

Istikhara is not performed by making the supplication immediately after the obligatory prayer. Scholars differ on whether it is sufficient for a Muslim to perform a supererogatory prayer, such as the regular Sunnah or greetings to the mosque, and then make the Istikhara supplication, or if it is necessary to pray two separate rak'ahs specifically for Istikhara. Some scholars say it is sufficient, while others say that a separate prayer is necessary, and this is the more probable view.