Random rule should be okay, if only the system picks the your 5 cards based on the highest possible star rating combination allowed.
For example, if you have above 30 but under 60, it should pick one card from the 4*-5*, plus 4 other 2* cards. If you have 60 cards and above, it should pick one card from the 4*-5* cards, plus 4 other 3* cards. Not a hand of 1* junks.