Is it considered tampering or indulgence to make up missed prayers at a non-fixed daily rate, while taking days of rest?

The status of prayer is great; it is the second pillar of Islam and the first thing a servant will be questioned about on the Day of Judgment. Neglecting it is a grave sin, and whoever has neglected it must repent and make up for it immediately. The majority of scholars hold the view that intentionally missed prayers must be made up.

You must hasten to make up these prayers, and make up whatever you can each day, provided it does not lead to neglect. Some scholars have set this at making up at least two days' worth of prayers per day, unless doing so would cause harm to your livelihood. Leaving off making up prayers without a valid excuse is considered negligence and dereliction of duty.