I used to always let mine air dry.
but then I realised that I wasn't washing them enough, and avoiding getting my hair wet all the time, coz it takes literally a full day to dry. so i was only washing my hair on hot sunny days when i had the time to spend the day outside in the air. if i stayed inside, my hair would still be damp by night.

so, a couple of months ago, i bought a cheap hairdryer, and it changed my life. actually, it's really good for killing lice too

that said, I never had a dryer till now, and my dreds are VERY thick - the thickest is about 2.5" thick, and they are mostly very very hard compacted, and the longest ones are to my knees (actually one is almost to my ankles). Most dreds aren't old and solid like that - they dry much easier.
mine have always been low maintenance. I got them through the neglect method, and never did anything to them except for a good wash in water only.

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