OOO increased the Radiant Crystal droprate, yet it's still hard to get them. The old droprate was nice if you wanted to get Radiants because they dropped mostly from the start(with some shining) of Tier 3, but that made it hard to get the 4* crystals. So we got recipes for crafting 4* out of 5*.
For some reason OOO thought that it would be a good idea to start the drop of 5* crystals on the later second half of tier 3.
This is a bad idea because you'll need to play tier 3 a lot to fully heat your 5* armor and you need to play the complete tier 3, which is fun because it takes a time to get to the later depths and your 5* armor is WEAKER than your 4* armor if it isn't level 6 or higher.
So I got this little idea:
Why not add a new startpoint after the terminal of each tier ?
One at depth 5
depth 14
depth 24
and a terminal before getting to the end of the tier:
depth 7(sells 2* recipes)
depth 17(sells 4* recipes)
depth 29(sells 5* recipes)
This way you can reach the later parts of a tier easier and the firecrystal drops could be changed like they used to be:
Depth 0-4 gives 1*
Depth 5-7 gives 2*
Depth 8-13 gives 3*
Depth 14-17 gives 4*
Depth 18-29 gives 5*
This way you would get the right crystals if you played arcade. 4* gear needs to be heated up to level 10, so it would make sense to get some crystals in tier 2. Tier 3 would probably have 4* crystals for the first few depths, but mixed with 5* crystals and a lot of 5* crystals on the later depths.
Or you can just run the missions that are in that stratum.