Play nomod if you genuinely want to improve, playing HDDT and farming won't make you a better player at all. If you really like going fast in general then I suggest dropping HD and playing a ton of DT on older style maps. A good way to find difficult DT maps to play are ones that don't have the entire leaderboard filled out with HDDT or HDHRDT plays. DT without hd is essentially just fast nomod, so that's why it works the same for increasing your reading speed and proficiency with higher ARs in general.
TLDR~ play nomod and farm less, if you're addicted to speed then go with DT on non farm maps pls.