This is a translation of Nidin's video (in Russian):
Please like his video, the author deserves it.
Here's a spreadsheet presenting the efficient strategy for crafting decorations (100% completion or to maximize credit boost, i.e. getting at least 72 decorations in each collection)
Levels 1-4 have 52 decorations each among 4 collections (13 in each collection). Count the total number of all decorations you miss at each level. Say on Level 1 you miss 5 decorations for New Year, 3 for Lunar, 7 for Magic and 4 for Christmas collection. Total is 5+3+7+4 = 19 left to craft. Go find 19 in Column F, then look at Column N.
Green color defines the best strategy. It's cheaper to craft lvl 1 decorations randomly until you get down from 19 to 10 missing decorations, then craft precisely needed ones for the last 10. You will get duplicates on the way, it's ok. On average it's a best strategy anyways.
Random crafting is where you fix the level (to lvl1 in our example) and leave collection and decoration type to be random.
To craft precise decorations, click on the missing decoration in the collection, it will take you to the collider with properly set up settings.
Similarly proceed with levels 2-4 according to the columns L-M, J-K, H-I.
Theoretical savings for each level are shown in lines 56 and 57 (This approach is based on probability, the estimates are YMMV).
The same approach goes with level 5 (see columns C-D) where the total number of decoration s is 160 now. Just use your 18 antiduplicators for the last level 5 decorations.
Note: Columns H-O show adjusted cost of crafting. Crafting precise lvl1 decoration costs 60 shards, but you later break it and get 10 back, thus adjusted cost is 50.