How many takes
How many takes will the band need to get it right? As many as are necessary, of course. There is no point in going any further and overdubbing to a backing track which isn't absolutely right. This is where your skill as a producer comes in. Probably the most important part of your role is to know when something is right, and this isn't nearly as easy as it seems. Absolute perfection is unattainable, but many successful records are less than perfect technically, with wrong or missed notes and rhythmic inconsistencies. Yet despite this they sound great! The producer should be able to spot a great take, even when there could be some musical errors. If you have captured such a take and recognise its quality, you then have to decide whether to use it as it is, or try and fix the problems. You can fix the odd duff chord in a guitar track with punch ins, where the engineer jabs the record button just before the section that needs to be replaced and, by hitting the play or stop button, punches out afterwards. Punch ins in a backing track can be noticeable where the spill from the other instruments suddenly disappears then comes back again, so listen carefully, and preferably have the engineer bounce the original take and the punch ins onto a new track for safety.
If the band has lost the rhythm at one point, then this is a bigger problem. The same thing applies if a take has started really well and has then broken down. In both of these cases, the solution is to edit the multitrack master tape and use sections from two or more takes spliced together. The engineer will do this for you while you pace up and down in the corridor outside if need be. Taking a razor blade to two inch twenty-four track tape is not a task for the faint hearted since if it goes wrong, then you have lost all. It hardly ever does go wrong however because the engineer will know from experience whether or not an edit will work. The main possibility why it might not work is if the tempo has changed from one take to another and there is a sudden gear shift. You can avoid this by getting the band to listen to a metronome ticking at the correct tempo before each take, or even getting them to play to a click track. This latter solution is rather drastic, and it is something that really needs to have been planned for from the rehearsal stage. Some producers regard editing as a creative process in its own right and will actively seek out the best parts from all the takes the band has done. I asked at the beginning of this section how many takes are enough. Since I know you are dying to have a figure, let me say that some bands have as few as three takes in them, and if they don't get it within those three takes, then thirty-three wouldn't be enough and it's best to move onto a different song and have another go on another day. Other bands really can keep going, and once they know that they have one take in the can which is good enough, they will relax and keep getting better and better.