PODs only happen to certain countries, usually Great Powers or English speaking nations and never in Latin America, Iberia, India, Eastern Europe (except for the Soviet Union), Africa (except for South Africa), or South East Asia (except for Japan or China). The only vanished civilisations that can have PODs are the Aztecs, The Romans and the Egyptians. PODs that happen before 1860 are possible but they never get developed into detailed timelines.
National leaders in ATLs are generally either supremely competent, or supremely incompetent.
Wars in ATLs are always ideological.
Only Anglo-Saxons can have successful capitalist economies. If other nations want to grow their economies they have to do so by conquest.
It is impossible for history to progress more than thirty years from any POD without a Really Big War. The nation that wins the Really Big War will be the dominant superpower for the next 500 years (or alternatively, until the next Really Big War in 20-30 years time).
In the real world, narrowly ideological philosophies of government and economics always fail, but in ATLs they always succeed.
Despite having failed fifty years earlier in OTL, in ATLs the Nazis stand a much better chance of surviving to the present day than the Soviet Union does.
ATLs never develop any alternative sports, popular fiction genres, popular TV formats, popular music styles, cuisines or religions.
Space travel must be much cheaper than we realise, because it is often economical for ATL societies with 20th century levels of technology to have bases on the Moon and Mars.
ATLs can somehow progress to higher technology than in OTL without causing any damage to the environment.
If the Roman Empire lasts to the present day, it will still have Gladiators. If the Ancient Egyptians last until the present day, they will still build pyramids. If the Spanish Empire lasts until the present day, it will still have the Inquisition. If the Confederacy lasts until the present day, it will still have slavery. If the American Colonies are still British, Americans will drink tea, travel in red double decker buses and be ruled over by effeminate aristocrats.