How long does it take you to finish a hard surface model of an object that you have never worked on before?

Hello!

As someone who has experienced in Blender making stylized object, I am used to finishing my model around 5 hours of work (for a cute character design for example) but as I am transitioning to learn Hard Surface modelling I was wondering how long does it take for people to finish an accurate model for objects that they arent familiar with :)

For example, you are tasked with making an Hammer Drill but you have never worked on this kind of objeect before. You try to search the internet but they do not have a tutorial for that specific model. What is the timeline that it would take for you to figure it out?

I would find this information helpful so that I can set realistic expectation for someone who is not experienced with this style of 3D modelling.