Is it permissible to consistently recite specific adhkar, such as Tasbeeh (glorifying Allah), Tahleel (declaring that there is no god but Allah), and sending blessings upon the Prophet (peace be upon him), without specifying a particular time or number, with the intention of gaining reward?

There is no objection to increasing the remembrance of Allah (dhikr), as Islamic law has encouraged it and promised a great reward for those who frequently remember Allah, in accordance with His (the Almighty's) words: "O you who have believed, remember Allah with much remembrance. And exalt Him morning and afternoon." (Quran 33:41-42) and "and the men who remember Allah often and the women who remember Him often – for them Allah has prepared forgiveness and a great reward." (Quran 33:35) Furthermore, authentic hadiths demonstrate the importance of dhikr and the virtue of increasing it, among them: "The Mufarridun have surpassed others." And they are "those men and women who remember Allah much." And "No human being has done a deed more saving from punishment than the remembrance of Allah." And "Shall I not inform you of the best of your deeds...the remembrance of Allah." And "that you die with your tongue moist with the remembrance of Allah."