Okay, so basically everytime I restart steam or go into this one specific steam account, it always starts to download Workshop Content. DLC unticked, files deleted. As you can see in the image below, my internet speed is slow, so sometimes I have to wait 30 minutes till I can play without lag, it allows me to start dota and play it, but it keeps downloading. If I pause the download it instsantly unpauses it and keeps downloading the update. It has been happening for about 6 months now or more, before the update was only 30 mb big, now it's 120.
The two things I know of that download as Dota 2 Workshop Content are Custom Games and guides. Guides are usually just a few kilobytes though, so I assume you are subscribed to Custom Games. A major update to one of these can be large.
Then click each game and the uninstall button. This will make them unavailable to play, but will prevent downloading these large updates for them that is causing you problems.