small bussiness`s , for eg , a scaffholding firm can only do 1 job at a time so this is called as concentrated marketing

You will not have as much wasted energy. This strategy helps you to determine the best places to put your marketing budget.

The concentrated strategy, which aims to serve a large share of one or a very few markets, is best suited for firms with limited resources

Well in marketing terms, concentrated marketing is targeting a large share of a specific segment (ie group of the population). For example, targeting a niche market, and trying to be the leader in that niche market. Undifferentiated marketing is targeting everyone with the same offer, and ignoring the different segments. So trying to sell your product to anyone that will listen, without worrying about if everyone will be interested.

Rolls Royce cars aim its vehicles at the premium segment, same as Harrods within the UK.