Hi massi1234
I don't know much about the ID90 tickets but the last two times I used the visa free travel at Shanghai (both 24 hours and 144 hours) the agent at immigration desk always checked my onward travel documents and circled the date of the onward ticket. My guess would be that you would need to have a confirmed seat and date on the flight. A quick check on chinatravelguide.com with the words "free 144 hours transit visa" seems to corroborate this. Others on here who have used an ID90 ticket may be able to offer more conclusive advice.
FQ