Isn't getting the timing right just "zap all the bits at the same time" ? Are these still basically a soccer ball of explosives encircling a core of subcritica

Isn't getting the timing right just "zap all the bits at the same time" ? Are these still basically a soccer ball of explosives encircling a core of subcritical nuclear material that "just" needs to be compressed? I think all of my knowledge of nukes might be based on https://en.m.wikipedia.org/wiki/The_Manhattan_Project_(film) https://en.m.wikipedia.org/wiki/The_Manhattan_Project_(film) xD