Notes from https://www.barrons.com/amp/articles/t-1-settlement-wall-street-b74fd6e2
Is there a reason why we don't have real time settlement in stocks?
It is answered in
real-time settlement is technically possible but eliminates important netting and financing opportunities in the market.
Notes from https://www.dtcc.com/dtcc-connection/articles/2021/february/04/why-shortening-the-settlement-cycle-will-benefit-the-industry-and-investors (published date: 2021-02-04)
Notes from https://www.dtcc.com/dtcc-connection/articles/2021/february/18/what-you-need-to-know-about-real-time-settlement (published date: 2021-02-18)
How to prevent brokers from lending your shares? In particular, how to do this for IBKR, Schwab, and Fidelity accounts?