A drain that keeps backing up is worth understanding rather than just clearing again, because the reason is usually the pipe itself.
Older homes: the pipe has narrowed
Cast iron drains in the established neighbourhoods build up a thick layer inside over the decades. A cable pushes a hole through the blockage but leaves that layer where it is, which is why the problem returns sooner each time. Jetting washes the pipe walls properly.
Newer homes: something went down it
In the more recent neighbourhoods the pipe is modern and sound. Blockages there are nearly always cooking grease, wipes labelled flushable that really are not, or debris left in the line when the house was built.
Groundwater in the line
On James Island, older sewer lines with cracked joints can take in groundwater, and that carries silt and grit along with it. Over time that settles in the low spots and adds to the problem — which is one reason drains here can slow down without anyone putting anything unusual down them.
When it is worth looking inside
If a drain has backed up more than once, a camera tells you whether you are cleaning a good pipe or postponing replacing a failing one.