@TimTim220 i do use premade textures, i have thought about using premade assets but... I don't know. Since i use this as a creative outlet i feel like using assets from other people would be like making a painting and having a lot of people painting stuff instead of me hahaha.
Of course, using pre-made assets is part of the game in the profesional field and theres a huge market for it.
SOMETIMES i do use premade assets from previous projects, like that bike and some barrels are part of other projects, and in the future i may use stuff from here.
So yeah, i would say what takes most of the time is making the models.