BLUF: Be ahead of the team on finding tasks and assess productivity.
No matter what development cycle you are using you have to be flexible in your taskings. The landscape is going to be ever changing and you need to adjust your team accordingly regardless of Agile, Waterfall, or whatever hybrid or static development process you are using.
The day before make a list, written or mental, of tasks for your team members. Take the time to apply skills and experience to tasks. Give each team member a specific list of tasks and suspense to go along with those tasks. It is super important that you give a task an assigned team member and a suspense date of the task. Each task needs those two pieces of information to be successfully. Everyone is happy to kick the can down the road if the task is not fulfilling so you need to give tasks a suspense.
If you make the tiny task list the night before you dole it out, then you can start gauging an idea of how productive your team is. These tiny tasks lists need to be tasks that don’t last for an extended time, such as “Build an API by January”. This task has too long of a runway, an ambiguous suspense date, and large feature task. You won’t be able to take simple metrics on productivity levels appropriately.
I am not saying you need to drag out a spreadsheet with VBA scripts running in the background or tracking velocity. This is good ol’ fashion feelings and best guess. As a leader you can quickly look around and assess the good from the bad in any situation if you have some understood information. If you cannot quickly assess your team skills at this very moment, then you are not paying attention to them or you are just not a good leader.
If you can ultimately find small tasks to give to your team and start assessing their productivity levels, then you can start assessing their talents, skills, and where they accel in their field vs. where they will struggle. In case you are wondering, getting coffee is not a task I am referring to. You should not be trying to haze your team, but if the tasks are within the responsibilities of the job, then by all means challenge and task away.