How long it taken for you to make a mod?

I wonder, is am I uneffective or its common if I doing realization of my big plans for my mod for a bit too long (as I personally think) even with such super easy tools as Mcreator and blockbench. So I wanna ask you about your mods :p

I wonder how long it take for you to make your mods? Are they as big as, for example, something like thaumcraft, mekanism? Are you worked on them somekind 24/7 or not?