We have a list of features, some of them are approved. Then we have a bunch of tasks, all have been estimated.
When we assigned to the developers, each of them starts with the
specific task, it might sequencial or parallel, depend on how the
project leader assign based on the design. But the tasks assignment
must be structural, priority base and load share. The objective is to
goal the Release Sprint, Release Version and Release Product
appropriatelly as in the project big picture plan.
When the developers have been assigned, on several tasks, and they progressing. The tasks should be updated to make the burn down chart progressing. At least daily, but maybe better on each step they have made the things finished (particular works). It doesn't have to be on each 100% finished to update the task.
If it doesn't updated daily, then you can see your burndown chart (BDC) like this below.
You will see, the slope is jumps drop from long period stagnancy at top
level. In this case in a week, the developer keep working on his tasks,
and maybe 2-3 tasks have been done, but no task has been updated since
task 1 or 2 finished. Then in the end of week, the dev update all
finished tasks at a time, the burn down chart then jumps. This is not
good.
We can't see the prediction of when the release will be ready as estimated before, and start guessing what are wrong; design? schedule? skillset?
The problem is, developer usualy thinks "I have to finish these, then update to the tasks assignments. I will then happy and my manager /supervisor will see it finally and happy". Wrong!
Also, if the reason is they have to be focus on the works, yes! it should be.. but spend a couple of minutes just to update the precentage of Progress or Estimated Remaining Time will not disturbing at all. That is the important thing. And simple!
If for some reason, a lot of tasks to do until we can't update the progress, then I suggest to use the automatic integrated tasks in IDE tool, to make it closer to the developers as in their code screen. Otherwise the project manager should slows down the task assignment 
, and find the matched rythm on the development speed... or think about resource replacement 
. Thats not good.