Main difference will be if they get banned or not. Manual will have less likely of account issues.
Manually can be better if its customized to the client which is almost impossible when you outsource to VAs as the language barrier usually doesn’t work well.
If you have a copy and paste script then automation will be the same as manual as long as the bot you use and proxies are good.
Going into hidden will also depend on how old your slave accounts are and how they were created in the first place. If you have solid slaves and good residential proxies, it should not be much of a difference between manual and automated operations.
Manual is good good but not scalable. We have 10k accounts now. So, even if accounts we doing 80 per day. We would still need a crapload of phones and assistance which means money, time and annoying errors.
Way too limited. Can be good for some F/U clients, but in order to run a big network, indeed that’s not the right strategy. Nothing that can be compared with a software.