The section is more prone to LTB is the load is applied above the shear center.
The effect of LTB is governed by the distance between the location of the applied and the shear center of the beam section. To see how the LTB failure propagates take a look at this video. openings involving bi-fold doors) which are prone to out of plane force effects.
The resistance to this twist is dependent on the torsional resistance of the beam section. Beams with large flange thicknesses, for example, have a greater torsional resistance than those of lesser flange thicknesses for any given depth. There are other sections that also offer greater resistance (RHS/SHS) and these are often used in situations where there is a need for large(ish) spans to carry the vertical load (e.g. The interaction of the compression and tension flanges forces an unrestrained beam to twist.
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