In my case, I had to consider the needs of the building at the top of the slope and put in terraces below one corner. This was expensive but I viewed it as preventive maintenance that saved money by avoiding a very serious and much larger problem. Other areas of the property have less steep and more stable slopes (and do not threaten to let a building cave in)and are being helde together with vegetation.
A lot of this depends on the characteristics of the particular slope and of the owner of the slope. Some slopes will fail without terraces, others can manage. Some landowners need certainty or formality (or their homeowner's associations and insurance carriers do), and some don't. FYI, I have seen mixtures of switchback trails and terracing. That compromise would allow for terraces and use of wheelbarrow. This application would only work in some settings however. Some slopes need interlocking walls, etc.