The prolonged continuous integration (CI) runs are affecting timely feedback to software developers. Test-case prioritization (TCP) aims to expose bugs sooner by reordering tests in the test suite such that the ones more likely to fail are run earlier. TCP is thus especially important for long-running test suites. While many studies have explored TCP, they use datasets of outdated CI builds (that are mostly over 10 years old) with short-running test suites (that last several minutes on average) or of outdated builds from inaccessible, proprietary projects. In this paper, we present LRTS, the first dataset of long-running test suites, with 21,255 CI builds and 57,437 test-suite runs from 10 large-scale, open-source projects that use Jenkins CI. LRTS spans from 2020 to 2023, with an average test-suite run duration of 6.5 hours. With LRTS, we extensively study 59 leading TCP techniques to identify the best ones on: longer-running test suites, TCP under the impact of confounding test failures, and cases where most tests have no prior failures. Our analyses revisit prior key findings (9 confirmed, 2 refuted) and establish 3 new findings.