Hi,
Actually I'm currently working as Wordpress Themes Developer in my office. I bid as personal web developer, not my company.
I've read your documentation, it's very clear for me, thanks.
I want to say, to build themes with high quality need minimum 3 weeks. I always make theme from scratch based on twenty fiften Wordpress default theme. I write code with Wordpress coding standard and use development + production CSS/JS in development. In production I always use minified CSS/JS. I always use Bootstrap and LESS/SASS in designing.
If you need to ask, please contact me, thanks.
Regards,
Ayub