I had an interesting conversation with my youngest son yesterday after dinner. Mum had cooked (a wonderful meal I should add…if she ever reads this), so it was up to me and my boys to wash and dry the carnage left behind.

I washed. I always do the sharp knives first – a touch of OCD according to my wife. There were a number of knives to wash.

No. 2 son picks up the first knife from the draining board, dries it and puts it on the side waiting for the second knife.

• Dad:“why haven’t you put that away in the knife block?”; 
• Son: “because I’m waiting for the other knives first”;
• Dad: “why are you doing that?”
• Son: “because it will be quicker!” (said in a tone of amazement at the apparent stupidity of my question)
• Dad: “why will it be quicker?” 
• Son: “because I will only have to walk over to the knife block once – duh!”

I let it pass, and carried on to see what happened. Here’s what I observed:

• He put the dry knife down on a dirty surface whilst it was waiting ‘in process’ – grrrr, needs washing again!;
• He waited (doing nothing) whilst I was washing the next knife. He and his older brother usually have a tussle about the next object, it’s desirability for drying and therefore who’s picking it up…I’m sure there’s a situational comedy sketch in there for the likes of Eddie Izzard!;
• He had created a pile (batch) of dried knives and then, somewhat dangerously, picked them all up and walked across the kitchen (bare foot), past his brother and I, and then tried to juggle them in his arms whilst attempting to slot them into the knife block;

• He nearly killed his brother in the process….though I can’t be sure as to whether that was his intent.

The funny thing is that we all seem to think, instinctively, that doing things in batches is more efficient. We don’t seem to see all the problems that it can create.

Whenever we deal in batches, we have to:

• create the batch;
• handle the batch; and then
• un-create the batch

…and, whilst this happens:

• items ‘wait’ in the batch whilst its assembly and disassembly is completed;
• defective items are masked until later in the process…at which point it is probably a problem for many, if not all, items in that batch;
• the whole batch suffers (is held up) whilst the item problem(s) are resolved.

I read a similar example on the ‘Leanthinker’ blog recently. It is another nice, short illustrative demonstration of the point.

I also highly recommend the wonderful 1980’s HP video that does much to show the sense of reducing batch sizes. It’s in two circa. 15 min. parts: part 1, part 2 (for info: there is a short ‘part 3’ as well)

Toyota’s phenomenal success (and other Lean Enterprises) lies to a large part down to its focus on the flow of each individual item, rather than the (supposed) efficiency of each activity within the flow.

A reminder that batches take a number of forms: they might be quantitative (e.g. when a load is full) or, more commonly in service value streams, temporal (i.e. at a point in time, such as monthly, weekly or daily)

Let’s see if we can re-programme our brains from seeing batches as a good thing to seeing flow as the ultimate prize.

I’m sorry to say that, after my ‘knife-juggling son’ observations, I attempted to explain the above to him and was accused (as usual) of “giving him a lecture”. I saw his eyes roll back in his head, I can’t win! I think mum was happy though: she was oblivious to the major life lesson being attempted.