Quote from reddit: 'When you craft a card of SR of UR rarity, you not only unlock the secret pack associated to it, but also get a free pack (once per secret pack). That's 47 more chance at potentially getting a UR that you can dismantle for free crafting points.'
List of craftable cards for free secret packs:
www.reddit.com/r/masterduel/comments/sd5za3/psa_craft_these_cards_to_get_a_total_of_23_free/?context=3
Fresh Account with 22k gems and 150SR CP / 150 UR CP for sale:
secretgardenofdreams.etsy.com