yeah, but there's one way of DID where, like you say the brain creates an alter for each event it can no longer handle.
then there's another form where the brain creates an alter or two, and then when an alter is going through something they can't handle anymore THEY create another alter...

..........BRAIN...........
......Event .....Event
........./ ..............\
....Alter ..............Alter

or:

.................BRAIN
...............|.........|
...........Event......Event
..............|.............|
...........Alter.........Alter
.............................|
...........................Event
..............................\
...........................New Alter formed by an alter

ok that's the best chart I can come up with under the circumstances. hope it makes sense.