There are different situations on which a variety of problems can be for analysis of Gravitational Field Strength due to Earth. In most of the problems one or more factor which is affecting the gravitational field strength due to Earth is considered and taken into account in the analysis.
There may be some situations in which it is asked to hypothetically change the dimensions, mass or rotational period (duration of the day) of Earth and the problem is asked on analyzing the effect on of g or vice versa. Also, problems can be asked on a value of g on other planets and information about that planet is given. In such cases, we can compare the parameters of the planet with Earth and by comparison with Earth we can evaluate the value of g on that planet.
Some situations are given below with example videos for an understanding of applications.
Effect of change in radius of Earth: https://youtu.be/tI656M_LacQ
Weightlessness at Equator of Earth: https://youtu.be/YLcoqCjqIFE
Half Weight compared to Earth Surface: https://youtu.be/xhDaXFfazeE
Oscillating Pendulum on another Planet: https://youtu.be/12fAUACg_F4