Some quick thoughts:

River bifurcation is probably something you should only use if you're really aware of how weird it is and yes if it's everywhere on you map you'd better have a good explanation for it. However I don't think it needs to be forbidden completely since at least one real world example had a real influence on human civilization.

The Amu Darya used to drain into both the Aral and the Caspian - the latter via a large distributary known as the Uzboy
( http://everything.explained.today/Uzboy_River/ ) which flowed from at least the 5BCE to the 18th Century CE. More importantly the Uzboy was navigable for most of its history so it was possible to ship goods from the Aral to the Caspian by water - just think of the world-building implications of that.

The Uzboy may also have been an early victim of the same hydrological mismanagement that has killed the Aral Sea rather than geology but I might be misunderstanding that.

On the subject of endorheic basins I think a lot depends on the size and position of your continents. A huge Pangaea like continent with lots of mountains and rainshadow deserts at the heart is going to have many watersheds where water simply can't reach the sea and either ends up drying up in the desert or flowing into an endorheic lake because gravity drew them inland rather than to the sea. A small continent less so but even Australia has Lake Eyre and the rivers that feed it https://en.wikipedia.org/wiki/Lake_E..._basin_map.png so it's possible, just less likely than on a huge continent.

Becka