If Magnus Carlsen, for example, faced Stockfish with the time control 1move/day, how well would Magnus do against Stockfish? It seems with so much time per move, tactical oversight disappears.
short answer: the computer would still win
long answer: a human player has much more time to think, well. but a chess-computerprogram would also have much more time to calculate much more variants. (and every good "classical" chess-computerprogram would use this time to evaluate as many variants as deep as possible). so the skill-difference would become linear bigger whilst you give them more time to think (assuming the players can use this time really prolific productively). the limits will be reached for a human when he wants to think deeper about more variants. for computers the limits a much broader because a computer would never be confused when it analyzes millions of positions.