Characters having flaws that make them make "wrong" decisions or conflict with other characters is good actually and getting rid of them is bad
kind of depends in my opinion? i think that sayaka's 'wrong' decision of panicking and trying to kill leon and frame makoto for it makes her a super interesting character that she would not have been otherwise. but something like kaito feeling betrayed by shuichi in chapter 4 of ndrv3 and starting an entire argument for it and leading to the Plot Mandated Friendship Failure was a wrong decision and conflict that was just completely fucking stupid and frustrating.
i think the difference being that i can delicately disassemble sayaka's wrong decision and see a well-oiled machine, while with kaito's wrong decision i can hear the fans whirring and the clunk-clunk-clank of the machine as it strains to run a webpage