I met a 337 owner at Jax, Craig field one day. He told of customarily starting and calling ground for his flight plan and other items before taxiing with just the front engine running, and starting the rear just before the run up. With just two young children and his wife, he forgot to start the second engine, and was surprised at how slow it accelerated, but at midfield, he had rotation speed, and took off. the climb was slow too, and then he noticed the tach on the rear engine at zero. He hit the starter, performance became normal, and he continued.
Those planes had a lot of surplus power when lightly loaded, and no asymmetric thrust to warn of single engine operation.
