The system you mention is the same. Clearing is done at the end of the day.

All that is exchanged during the day are IOUs (debt) and if one player in the chain goes bankrupt during the day the central bank might cover its debt up to some limit.

We haven't had any major crisis since those instant pay apps were put into place. So those aren't really battle tested systems and I guess we'll only effectively discover how resilient they are during the next crisis...