I'm from PLC land and have had it drilled into me to turn my stock ASAP. I stock 10-12 cars and sell 14-16 a month. for me its all about getting the ££££ back in the bank as soon as possible. I premium Price for 10 days, then re look every other day. If i've had a car in stock over 120 days i'd get rid for cost or a small loss as i'd rather have it invested in something else. My average days in stock for 2017 was 28 days, which I can live with as I did have a couple of terminally ill cars that went 200 days or so!
PLC would write down at 30/60/90 days ( in fact you'd get a fine of £1000 per car at 90 days, so it didn't happen )
Sometimes stuff flies away in minutes, but others stick, I try to take a lesson from each car I buy, every day's a school day so they say....