Gems for different activities

Is it advisable to use gems based on the activity at hand

for example, to strengthen Mars in the chart when undertaking a day of strenuous physical labour? (And would there be a difference if the work were a once off vs. on the same day each a week*?)

my Mars is in Leo so this would be a good place for this use, but in general is it better to strengthen the planet (Mars for this example) in the Rasi of your birth chart, or say if I had Mars in Cancer to wear a Mars in Leo or Aries gem regardless? 

* to get even more particular, would the karaka of the day (Monday moon etc.) have any effect on gem selection for this ‘same day each week’ selection)

Thank you ????