Stopping at al-Abtah is not a sunnah. The Messenger of Allah ﷺ only stopped there because it made his departure easier when he set out.
نزول الأبطح ليس بسنة، إنما نزله رسول الله ﷺ، لأنه كان أسمح الخروجه إذا خرج.
Bukhari narrated it in the Hajj chapters (1765), and Muslim in the Hajj chapters (1311), by way of Hisham bin Urwa, from his father, from Ayesha, and the wording given is Muslim's. Muslim also narrated it by way of Zuhri, from Salim, that Abu Bakr, Umar, and Ibn Umar used to camp at Abtah.Zuhri said, Urwa told me, from Ayesha, that she did not do that, and she said, "The Messenger of Allah ﷺ only camped there because it was a place that made his departure easier."His saying, "Abtah," refers to the flat open ground between Makkah and Mina, that is, the part of the valley that opens out and widens, and it is the same place that is called Muhassab and Muassar. Its boundaries run between the two mountains up to the graveyard. Muhassab, Abtah, and Khayf Banu Kinana are names for one and the same place.