On-the-fly multistage adaptive testing (OMST), which integrates computerized adaptive testing (CAT) and multistage testing (MST), has recently gained popularity. While CAT selects each item on-the-fly and MST bundles items to pre-assembled modules, OMST assembles modules on-the-fly after the first stage. Since item selection algorithms play a crucial role in latent trait estimation and test security in CAT designs, given the availability of response time (RT) in the current testing era, researchers have been actively striving to incorporate RT into item selection algorithms. However, most such algorithms were only applied to CAT whereas little is known about RT’s role in the domain of OMST. Building upon previous research on RT-oriented item selection procedures, this research intends to apply RT-oriented item selection algorithms to OMST. This study found that the relative performance of RT-oriented item selection methods in OMST was consistent with CAT. But the underlying item bank structure and test design features can make a huge difference with respect to estimation accuracy and test security.