Not for network folders it isn't. And indeed this is one of the most annoying parts of Marlin: when browsing any kind of networked folder (SMB, SSH, FTP...) and something other than Marlin changes the contents, it is necessary to completely restart Marlin for the changes to be shown.
At the other extreme, Nautilus refreshes the view on every single folder change. This is very slow. I think a happy compromise would be to include a refresh option (F5 or Ctrl-R) and let us force a refresh of the folder view. Currently, Marlin's behaviour makes it very painful to use in these situations.
There's a Reload option in the view menu (Ctrl-R hotkey) in 0.1-0~818~precise1. Don't know exactly when that feature appeared, but I'd wager that closes this bug.
It is not sure, since all is refreshed in real time… Maybe only for network folders.