This is a great question, @jean, and one we hear from customers often. There’s another great post here about different integrations community members use for this: Do you track your time? - #11 by dickvandruten
If you want to track in Asana, I’d recommend setting up a project with a field for estimated and actual hours. I do this up to 15 minute increments (using 0.25, 0.5, 0.75, 1 etc.) and have effectively been able to resource plan and track work across the different categories of projects I work within. You can see an example of this from my live project here:
Do you think something like this might work for your needs?