How long do great bridge players take to play?

There does not seem any relationship between speed of play and ability. From the earliest newplicate game to the world championships, some play fast, some play slowly. (Me? I don't know what I'm doing, so I do it fast!) I think it relates more to personality and mental style than to bridge ability

In international tournaments it's pretty normal for about 8 minutes to be allowed per hand. Matches are often played in sets of 20 boards so this is only the average time that players will spend on one deal - there will be many fast claims and a number of much slower hands played - the slowest that I have seen was my team mate taking 49 minutes over a deal in a Junior European Championship (although you may well not count this as expert level). In my experience expert players usually think for a minute or so when the dummy comes down and then play fairly quickly if they are declaring. If a hand is particularly tricky or if an unexpected development occurs a player may well think at a different point or for longer. Part of the skill of an expert player is in knowing when to think and in recognising when taking the time to think is still helping them and when they are no longer improving on their existing line of play (sufficiently for it to be worth the time investment).

For the declarer: When the dummy is laid down, the declarer figures out losers, winners and the does a general simulation of how play might go, what is called "planning of the hand". This takes a little time. After this, normally one goes on playing at a good pace unless something untoward happens (a bad break is discovered). For the defence : The pace is likely to be a bit more uneven since the defence does not have automatic coordination between partners. Often, there is more to think about when the defence has to lead, both at first trick and there after to find the right shift when the chance comes.

Fulvio Fantoni, currently ranked #1 player in the world, is also considered one of the slowest players. Bridge etiquette requires to play "in tempo", and a break in tempo when bidding or defending can be a reason for a TD call (which depending on the situation can carry a penalty if the TD judges that unauthorized information was passed to partner). Expert players don't stop often to think as this would be a breach of the above, but don't rush either, usually taking a couple of seconds for each play. When they do stop it usually happens in the beginning of the play, after the dummy is tabled, and possibly either in the middle of the hand or towards the end if they need to reassess the situation (and usually announce this to let the opponents know).

In general, players at any level should play in tempo. An extremely long time before a bid can convey information to partner and that's unethical. However, some bids (and plays) aren't easy and it's permitted to "go into a trance" before you bid or play. There is a limit. If you feel a player is taking too long on what should be a simple response, call the director. They'll probably get away with a warning.