LSM stands for 'Lean Startup Mentality'. The Lean Startup approach championed by Eric Ries is - as the name implies - targeted at startup businesses, but has methodologies that any business can apply to new products or services.
I have had direct experience of a startup business that did not adhere to a lean startup process and consequently chewed through over $10M funding before discovering that it has designed an unsaleable product.
A Lean Startup Mentality encourages businesses to get to the real world fast, rather than spending a lot of time and money on developing and refining a product or service that it turns out nobody wants. Launching with an incomplete 'beta' version of your product allows you to go out to a select group of potential customers and see if any of them are prepared to pay cold hard cash for it.
If not, you may need to 'pivot', that is look to see if there is a way you can tweak your product to make it more useful or maybe even see if there is a different group of people who would be prepared to pay for what it does.
Mike O'Hagan, the founder of Mini Movers, has a similar recommendation. He suggests you distribute 1,000 leaflets to your target market (in his case this would have been homes in the area) and wait to see if the phone rings. If it does, you have a business. If not, think again.
In all cases you're not spending an inordinate time developing a product that nobody may want and you are not spending a huge amount of money on promotion or marketing until you have had some validation that there is a market for your product/service.
Next time (and last in this series)... BS (not what you think it is).