Our Tesco doesn't reduce things by much.
Bum
Does depend what time you go though, and sometimes you've got to be prepared to hang around.
It does vary from store to store, but a good rule of thumb is first reductions for chilled, fresh counters, pre-packed bread and fruit & veg is 10 am. That's not usually worth is as may only be 10 to 15% off, if that. Second reduction kicks in at around mid afternoon and that's around 30 to 50%. Then you get the final markdown (between 75 and 90%) in the evening on what's left. ISB only gets marked down once at tea time and that's a straight 50% off. Likewise the cooked chicken counter, 50% off unless there's a lot of stuff that's not sold.
During the week, best times are in the evenings for the big markdowns but it can be very pot luck. Sometimes there's loads, sometimes there's very little left. On Sundays and Bank Holiday Mondays, from around 1pm onwards, though depends a bit on closing times. If there's a lot of something and they need to shift it quickly, you can get up to 95% off...
And if the weather is hot, you know it will be all casserole meat, tatties and root veg. If it's cold and wet, it'll be burgers, rolls, soft fruit and lettuces...