It is very important to note that by throwing the pebbles, one emulates Prophet Ibrahim (peace and blessings be upon him) when Satan blocked his way at that place in order to cast doubts in his heart or tempt him and divert him away from his Lord. For this reason Allah commanded Ibrahim to drive Satan away by throwing pebbles at him.
Sheikh Sayyed Sabiq states in his well-known book Fiqh As-Sunnah: It is desirable to stand facing the qiblah, to praise Allah while supplicating to Him for forgiveness for oneself, and for one’s fellow Muslims. Ahmad and Al-Bukhari have reported from Salim ibn `Abdullah ibn `Umar and he from his father that when the Prophet (peace and blessings be upon him) threw pebbles at the first Jamarah which is near the mosque, he said, “Allahu Akbar.” Thus he threw seven pebbles and each time he said, “Allahu Akbar”. Then he went and turned left toward the bottom of the valley. There he stood for quite a long time facing the direction of the qiblah, and raising his hands he supplicated to Allah. Then he went and threw seven pebbles at the second Jamarah saying, “Allahu Akbar” with each throw. Thereafter he went to the left of the bottom of the valley, stood there facing the qiblah and supplicated to Allah with raised hands. Then he went to the Jamarah near Al-`Aqabah, threw seven pebbles at it, uttering a Takbir with each throw. After this he left and did not pause. According to this hadith the Prophet (peace and blessings be upon him) did not pause after throwing pebbles at Jamrat Al-`Aqabah, but he did pause after throwing pebbles at the other two Jamarahs.
The scholars have, in the light of the above hadith, suggested that after any throwing of the pebbles at the Jamarah that is not followed by another throwing on the same day, one should not stop (for supplications), but if throwing (of pebbles) is followed by another throwing on the same day, one should stand there and make supplications.
Ibn Majah has reported from Ibn `Abbas that after throwing pebbles at Jamrat Al-`Aqabah, the Prophet (peace and blessings be upon him) used to leave, and not stop (for supplications).
Allah Almighty knows best.