[dontknowme]

Likely. Kitchen ovens and small ovens in general do not have the accuracy required to reflow. As you say, they will cycle between full power and no power and rely on the large oven hysteresis to get an average temperature which is OK for cooking, but can be easily off by 10+C at times, even if ventilated.

One solution is to wrap the item in something which acts as a dampener. A couple of layers of crumpled tinfoil will help.

Note that you definitely can reflow in a low-end kitchen oven with the appropriate changes ;). I built two small ovens for reflowing. Search for "arduino reflow" for some pointers.