I'm also wondering if anyone's found any tips to help with this. For example, does it help if toilet and restaurant are in the same building group (the way scenery calculations often happen). Or, does placing the toilet near the restaurant entrance/hallway, rather than on the side/back, help? Alternatively, is it that the draw of the restaurant is too high (so excited to eat!) that they forget everything else when they're near it.... and suggesting that in addition to restrooms right next to restaurants (like in real life), we may also need to be placing some at a particular distance away from the restaurants, just outside of the radius where guests start to get pulled in, so that more guests who do enter the restaurant radius start with emptier bladders?
If it's simply that guests are staying too long that their restroom need calculations plummet over time (like animals who are "stressed" because they fell asleep where guests can see them), then I guess I can accept that. After all, some of us do act like four year olds some of the time. LOL! But I'm legitimately interested if there's a in-game management solution that we just haven't thought of yet. (similar to how bedding can influence where animals sleep, in my stress example).
