CSS still requiring clearing cache after following steps to switch caching off I have followed the steps detailed in this tutorial and many others -> https://knackforge.com/blog/rajamohamed/disable-drupal-8-cache-during-development

I have copied and renamed the sites/example.settings.local.php file as sites/default/settings.local.php

Opened settings.php file in sites/default directory and uncomment these lines:

if (file_exists(__DIR__ . '/settings.local.php')) {
  include __DIR__ . '/settings.local.php';
}


I have uncommented the following lines in settings.local.php to disable the render cache and dynamic page 

$settings['cache']['bins']['render'] = 'cache.backend.null';
$settings['cache']['bins']['dynamic_page_cache'] = 'cache.backend.null';


I have opened development.services.yml in the sites folder and added the following lines (to disable twig cache)         

parameters:
  twig.config:
    debug : true
    auto_reload: true
    cache: false 


I have then cleared cache, this has worked for twig it seems as I am able to make changes in my page.html.twig and these update on a standard browser refresh.

However, any changes to by CSS files are requiring a clear cache every time, slowing development down quite a lot over time.

Hoping for some help here.
Written by @Clive in the comments


  Are you using chrome? Asset caching got way more aggressive recently
  for some reason, if you're using it try opening the Network tab in dev
  tools and selecting "Disable cache"


This solved me the problem.