It helps to know if a drive to the store is going to take 12 minutes or 2 hours as I am trying to schedule my errands for the week.
Likewise, when planning on working through a learning module, task, or activity it helps to know how long (about) it will take to complete. The dedication to "time on task" is easier to make when I, as a learner, know how much time is going to be required. Like my trip to the store, it will have a big influence on how I plan my time and how I prepare myself.
This is why I add an estimated time to complete (ETTC) to actionable items in my courses.
I have found that ETTC helps learners overcome their procrastinations by eliminating some of the ambiguity of what time a commitment to action entails. Considering the messy schedules they often have to navigate, its useful for to know if they can squeeze a chapter reading in before their meeting that starts in 30 minutes. If they don't know that it only takes 10-15 minutes (on average) to read the chapter, they likely will not even bother. ETTC enables them to pace and schedule their engagement effectively.
In addition, an ETTC provides them with a measure to compare their own time on task to. If it is taking a hour to complete something that should take 10-15 minutes this would be a red flag that something is amiss.
Did I mention that ETTC should be a range? It should be a range. Because you are bad at estimating. If you know the time to complete then its just TTC. Which is fine too.
We've seen a commitment to communicating time to complete work well elsewhere; from cooking recipes to time stamps on videos. ETTC is useful information for making a decision about when or whether to engage with something. Its also useful to know that this recipe should only take 20-30 minutes, but I'm on day two, something is wrong.
I'm not going to spend another two days making Pasta de Pepe but I will watch an informative 3 minute video.
Time is a cost and learners want to know how much they are paying.
note1: ETTC helps schedule, pace, prepare, compare
postscript1: Don't get too macro with your ETTCs. Try to provide an ETTC to each actionable item.
postscript2: Use learner feedback to improve your ETTCs.