If there was any doubt, with the 1939 setup, some powers start with tech at stage 1 or 2, for instance Japan has Long Range Aircraft (Stage 1) and Heavy Battleships (Stage 2).
Therefore, all other tech are at zero (no marker on the Technology Chart), so you indeed need four successes to complete a tech.
Also remember that if you start in 1936, you cannot research beyond stage II before July 1939 (Rule 7.6 and Global War Tech Sheet), which should also prevent all nations from ending up with all the techs.
I have yet to see a game when even the technology superpowers like Germany and the USA have acquired everything.
