HENDERSON, Nev. — It took four hours on Saturday afternoon to count just 4 percent of the results from the Nevada caucuses.

That didn’t stop The Associated Press from calling the state for Senator Bernie Sanders, but it did cause a lot of confusion — and continued to do so late into the night — about why counting caucus results takes so long.

Officials with the Nevada Democratic Party and the Democratic National Committee stressed all week that they had gone to school on lessons learned from the bungled Iowa caucuses, when a smartphone app for reporting results crashed and phone lines to report results were jammed for hours.