Put them in a bucket to soak for weeks, or months? YES that IS crazy talk!
As has been said, if you have something that is really filled with crud then do a soak that day, rinse it well, then hang it out to dry. Only AFTER towel are dry do you store them away in a bin, box, bucket, whatever. If you put wet towels in a dark, damp place they'll all mold and ruin them.
I can't say I'd put any fabric softener in them either. By default they are made of millions of little hooks and loops and those little hooks and loops will totally fill up with the fabric softener over time. It *may* make them feel softer, and less 'grabby' on your hands... because they are filling up if no other reason.
Using your washer on delicate, with a small squirt of liquid detergent and a squirt of Woolite will get them clean. Storing them with residue from compounding, polishing, even using a LSP isn't going to hurt them however.
More importantly would be to 'grade' your towels as you uses them. After they are dirty separate them into different 'grades' depending on what and how they were used. If they only did paint duty, and only on the upper portions of the paint, then obviously they are the cream of the crop and should NEVER be mixed with other towels. If they get a little dirty, but don't do door jambs, rocker panels, or even clean wheels then they'd be your next level of towels. Same thing for the next level, the ones that do get jamb duty, rocker panels, grills etc. would be in their own bin. And finally the dirty ones, dirty wheels, lower rockers, exhaust, any mud or dirt and that's ONLY what they do from then on. I keep 4 boxes for mine and each time I use them they'll get put into the appropriate box after using.
Not so much sorting and grading for your higher end towels. Really is easy to know say your 700's are only for LSP duty and thus they get washed with other LSP only towels of similar construction. That being said, some 530's are good for early (dirty) work, including rinseless washing as well as LSP work. Those should be separated and washed with the others that are used for similar duty.
The key is expensive towels tend to only get the same job time after time. Where lesser towels may be good for (some) paint duty the first time or two around and the more they are used the more they get demoted to lesser duties.
