How often does the National Commission for Scheduled Tribes present reports to the President regarding the working of safeguards provided for the Scheduled Tribes?
According to the context provided, it states that "it shall be the duty of the Commission— (5) It shall be the duty of the Commission— (a) to investigate and monitor all matters relating to the safeguards provided for the Scheduled Tribes under this Constitution or under any other law for the time being in force or under any order of the Government and to evaluate the working of such safeguards; (b) to inquire into specific complaints with respect to the deprivation of rights and safeguards of the Scheduled Tribes; (c) to participate and advise on the planning process of socio-economic development of the Scheduled Tribes and to evaluate the progress of their development under the Union and any State; (d) to present to the President, annually and at such other times as the Commission may deem fit, reports upon the working of those safeguards."

From this it can be deduced that the National Commission for Scheduled Tribes must present its report on the working of safeguards provided for the Scheduled Tribes to the President annually. However, they also have the option to do so at other times when the Commission deems fit. Therefore, there is no specific frequency mentioned in the text but it seems that an annual report is mandatory and additional reports can be submitted as per the discretion of the Commission.