If you are going to mic up an amp or cab then it is better to record all of the parts for all of the tracks at the same time - at least if you want to have the same guitar tone throughout the entire album. Same goes with the drums.

If you are recording direct though, the beauty is that you can go to the studio once a year and use the same settings and guitar and it will always sound the same.

You recording at homeor in a studio with an engineer? If its in a studio then you should wait a couple of months before commiting to a session - the tracks should grow and change with practice. If it's at home and you are recording direct then that is no problem, just jump back in and make the fix or add the new section as you please. It's much easier to arrange at home, then when you are 100% happy you can book studio time. A word of warning though, it is very time consuming in a studio so unless you have the parts down 100% and can nail them within a couple of takes you will waste all of the time trying to do punch ins where you could have been getting the engineer to work on the mix (speaking from experience). I only go to the studio now when I can play each track and solo through without making any mistakes so I can make the engineer work on the mix and not waste valuable time on editing.

Hope that helps.