Even if they don't block your loo, they cause obstruction in the main, and will block eventually,
especially bad if you have cracked pipes, which a lot of insurance companies have now found a way of not paying for repairs which are very expensive,
never put anything in the loo you haven't digested, that and loo roll, everything else does a lot of damage.
but as a builder, do feel free to create as much work as possible, but I would rather not do drains.
it's partly why now when advising clients on property before they buy, we always do a full drainage survey, because drains are ruined by inappropriate use, fat, nappies, wipes, q-tips, quickly mean that you will have problems,
when you buy the insurance you take out, rarely covers drains in the first three to six months, and people ignore as it such an upheaval, so when you buy make sure drains are covered, as it is always really labour intensive work, which takes time ,all while you have no loo, cost loads, and most builders avoid doing it like the plague, which is why I make my clients do theirs in advance, so we avoid doing it when people further up pipe keep flushing their loos.
You are responsible for your sewer pipe until it joins the main, add lots of inspection hatches (they are now an easy clip together lego like product), if you ever replace this section, you can't have to many, it means all future problems are very easily and cheaply solved.
and ban people who put tissues, dental floss, hair, fat, nappies, tampons, sanitary towels and cardboard from using your facilities, it will save you a fortune, and your save the day when the loos back up.