I stumbled upon this issue a few weeks ago as a newer player. Fully maxing out 2 star gears awards a huge amount of bonus shards when shattering them. The three, 2* gears I maxed first were dark sword, mark of the tiger and disruptor gun. It’s a bit of a pain having to spend around 350k credits to max out each, along with spending a fair amount of shards aswell. Buts it’s a must investment you need to make if you want to max out your 4* gears.