A comparison of pacing contingencies in classes using a personalized system of instruction.

The researchers ran a university course under two pacing plans. In one plan students faced many small deadlines spread across the term. In the other plan they faced only one big deadline at the end.

The class alternated between the two plans so each student experienced both. The team then counted how often students took unit tests early, on time, or late.

Multiple small deadlines kept test-taking steady. Students took tests week after week without bunching up.

A single end-of-term deadline created a scallop. Most students did nothing for weeks, then crammed all tests into the final days.

Bird et al. (2021) later asked the same pacing question with a new tool. Instead of deadlines they gave or withheld access to study slides. Both studies found the same core result: tighter contingencies cut procrastination.

Stoddard et al. (1971) saw the same scallop earlier. They compared daily, weekly, and three-week quiz schedules. Long gaps produced the same last-minute rush that L et al. saw with one deadline.

Mutchler et al. (2025) moved the spacing idea to skill maintenance. They distributed follow-up sessions instead of deadlines and again showed that spread-out events beat massed ones.

If you write course calendars, train staff, or coach older learners, chop big due dates into smaller ones. A quiz every week, a module gate every five days, or a progress check every third session keeps work flowing. One distant deadline almost guarantees a rush at the end and weaker learning.