Answered by Shaykh Faraz Rabbani
Should one say the supplication of entering and leaving the mosque when one enters/leaves a prayer room?
Walaikum assalam wa rahmatullah,
This would not be a specific sunna–because the sunna itself related to entering and leaving a mosque. However, there is no harm (and much reward) in doing so out of a general desire to engage in remembrance of Allah.
And Allah alone gives success.
Wassalam,
Faraz Rabbani