Actually the central planners did plan backups and alternatives for everything. With all its flaws even the SU was not so flawed to let total idiots make every economic decision.
Just think of Mig and Sukhoi, for a simple example. Or NPO-Saturn and Tumansky, if you prefer jet-engine manufacturers.
> not so flawed to let total idiots make every economic decision
You might want to read up on Khruschev's corn farming plans, Gorbachev's prohibition, Mao's backyard furnaces and many more. Slightly tangent, check on Trofim Lysenko's anti-genetics antics. USSR style socialism explicitly declared ideology over science, engineering and what not. And by ideology they meant whatever The Great Leader says.
Just think of Mig and Sukhoi, for a simple example. Or NPO-Saturn and Tumansky, if you prefer jet-engine manufacturers.