Skin Shards Likely Won't Get You What You Want
RIOT tried to play it off as if you'll be getting a lot more champ deals because you're getting more skin shards, but this is really just an illusion. Almost everyone will have the cheap 450, 1350 and many 3150 champs. It's the 4800 and 6300 champs most people are missing due to their high cost so early on you'd get all the 450s at minimum just to get the champ count minimum up to do ranked
First, a couple baselines to get us started. A Leveling Capsule contains champ shards with a BE value of either 720, 900, 960, or 1,240. (The average value is 910 based on drop rates) A Milestone Capsule (every 10 levels) contains champ shards valued at 1,980, 2,160, or 2,220. (The average value is 2,120 based on drop rates)
http://www.surrenderat20.net/2017/11/red-post-collection-preseason-runes-722.html
Also based on the average above of 910, I figured out these: 20% to get 720 Capsule 50% to get 900 capsule 20% to get 960 capsule 10% to get 1240 capsule
720 has now been hotfix bumped up to 810 since it was deemed too low, but that doesnt change anything regarding 6300 champs.
The ONLY way you'll get a 6300 champ shard is if you get the 10% chance for the 1240 capsule on leveling, and when it's a 1240 you only get ONE champ shard so you better hope you first hit the 10% for a 6300 champ then hit the odds it's for one you dont own. Those who are getting 3-5 shards in their capsule are because theyre getting shit 450 cost champs. You WILL NOT be getting 3-5 shards of 6300 cost champs
At best if you dont own any 6300 champs, you're at 10% to get one (shard too, not the full champ so you'd need to DE several levels worth of capsules to unlock it). Worst case if you're just looking for 1 of those 6300 champs you'd be at 0.3% odds of getting the shard
Also, the milestone capsules still wont contain more than one 6300 shard as the DE cost is 1240. 1240x2 = 2480 which exceeds the highest DE value of the milestone capsule