Voyager was very inconsistent in a lot of things. Early on, it was established that the complexity of a hologram like the Doctor was to difficult, and if they ever lost him, they'd be FUBAR'd. Then, later in season 4, there's an episode set several centuries later, where a back-up of the Doctor is found on an alien planet. Quite odd.
In season 5, they whip up a medical consultant for the Doctor, using information from the computer, who's a complete interactive hologram capable of making decisions on his own and the abality to perform complex surgical techniques.
So basicly, to answer your question..... there's no clear answer.