Can you avoid voice dubbing (post-production) and do direct recording while shooting a film with improved equipment? This would save a lot of time and energy. This would also ensure natural reaction. (You can go for dubbing for real problematic portions only, if required.)
Direct recording is already done, it's just that under some conditions the voice needs to be re-dubbed. This might happen on a windy shoot where sound waves are carried from the mic due to the wind, and the mic may pick up more ambient sound than the actor's voice.
This is what boom mics are used for!
Post-production dubbing is mostly only done for problematic portions, as you stated above, or for using an alternate audio such as a foreign language. Also, post-production dubbing is used for altering dialogue for TV broadcast, when the dialogue would have garnered the movie an R rating.