Not very experienced in lith, just used LD20 in regular dilution (+ "old brown"); also tried Fomabrom Variant and got 20 minutes developing time at 20C and very, very grainy. 20 minutes just too much!
Got the advice her on APUG to heat up. I changed paper to Fomabrom 131 and at 25C I got nice developing time like 2-4 minutes and, at least, sometime interesting results (some posted at the Standard Gallery). Have just ordered some Fomabrom 111 graded paper, grade Normal, which they say is nice for lith, haven't tried it yet.