In fact, the natural planning claimed by the GTD system does not really imply accurate time estimates or a strict structure, but as we all know deadlines are deadlines and those around us expect what is done by a certain day, hour, minute. And this is not surprising. The time of execution is important precisely when our affairs are connected with other people. Therefore, even when planning in GTD, when everything is focused not on deadlines and time, but on the actual execution, it would be nice to at least roughly take into account the time required for the task, otherwise you will have to forget about the delivery of tasks on time.
Since we cannot pay much attention when processing Incoming evaluation tasks, I suggest crossing the notorious concept of time-boxing and the actual preliminary assessment. That is, when considering a task, before sending it to one of the lists for your own tasks, you should very roughly estimate the time required to complete it in the time-box.
For myself, I chose 15 minutes as the minimum value, but another period of — half an hour or five minutes — may suit you.
For a quick assessment of tasks at the stage of planning the next steps, I suggest visualizing a time estimate. For GMail, labels will be the natural and only way to do this.
They can look like this:
By adding such labels to the tasks, then, when parsing the lists, it is very easy to estimate at a glance the amount of work that can be completed for a given period of time, which will allow you to fulfill promises without stress.
But still, the most important mistake that I left for sweet — is doing nothing. Do not complicate the system — start to execute what is planned, what is not needed for your planning will disappear by itself, and you will add what is missing to make your work more convenient later, as you understand what helps you and what hinders your work.