So, for a long time now I have used the idea that the first few game sessions for a character are fluid.After the character's been played even for just a few sessions, however, everyone else at the table has the patterns, personality, maybe alignment, etc. you've established in play to measure against.
The advantage of this is that you can use those first few sessions to determine if what you've got in your head is going to work out at all well in play, and - before you've locked yourself in too much - tweak accordingly if it isn't.
I have seen so many players come over with some "great" idea for a character.....and hate it after just a few hours.
As I play Hard Fun Unfair Unbalanced Old School style, it is very common for PCs to die. And also common for the player to come back as "Fred II", basically the character that just died but with a tweak or two