Lightning is a giant spark of electricity in the atmosphere between clouds, the air, or the ground. In the early stages of development, air acts as an insulator between the positive and negative charges in the cloud and between the cloud and the ground.

The amounts of electrical energy traveling between cloud to cloud or cloud to earth, containing an average charge of 3,000,000 to 5,000,000 volts, a current of 300,000 amperes and a speed of 22 km/s. Even though a lightning discharge is of a very short duration (typically 200 microseconds) it is a very real cause of damage and destruction.

The function of an external lightning protection system is to intercept,
conduct and disperse a lightning strike safely to earth. Without such a
system a building’s structure, electronic systems and the people
working around or within it are all at risk.

There is no direct answer to this question. However, there are different standards e.g. NFPA78o (USA), BNBC (Bangladesh), IEC, IEEE etc. which dictates different classes of construction and usage of LPS according to type, use, location, importance, make etc. Only an expert can determine if a construction will require LPS or not.  

Bangladesh National Building Code (BNBC) first proposed in 1993,
made it mandatory in 2006 and a legal binding in 2015; gives clear
regulations for setting up “Lightning Arrestor” recommended for
buildings over 22m high and mandatory for buildings more than 33m
high.

Fire Service and Civil Defense department and, Public Works Dept.
(PWD) of Bangladesh government are working relentlessly in lightning
awareness and protection in common people. It is obligatory to take
the NOC (No Objection Certificate) for all realtors which comply with
BNBC code.