As @johnnybike mentions they don’t affect future recommendations directly. They are workouts designed to test your “hardness” similar to the way BT workouts are designed to test your “fitness” and generate a BT.
Note these descriptions from the workout library and click the reference links below –
Xert’s Hardness Tests are workouts that test your toughness and ability to produce power under central fatigue. These workouts need to be performed precisely in order to be able to properly compare one result to the other. Levels 1-3 are generally for those recovering from injury.
Alternate: If the standard Level xx test is impossible given your Fitness Signature. Use this test as an alternate.
Levels 14-18 are extreme hardness tests. These can only be completed by athletes that are highly-trained. motivated and exceptional.
Reference:
Hardness – Xert (baronbiosys.com)
How Tough Are You? – Xert (baronbiosys.com)
Hardness test - order - Support - Xert Community Forum (xertonline.com)