the general weekly approach is:-
3 runs - inc 1 longer run building from 30 mins to 2.5 hrs over your program
3 swims, - inc one building to 1 hr 15 mins / 3.8k over your program
3 bikes - inc one longer one building from 90 mins to 6 hrs over your program. Second medium ride to include intervals.
Thats 9 sessions in 6 days as its nice to have a day off. So many days will have 2 sessions a day, (no one fancies too much else following a 2.5 hr run or a 6 hr bike)
with a long run / long swim and long bike as key sessions each week.
Add stength core if you have time
If you really have more time, bike lots more and run a bit more
Gordos 'basic week', Friel's 'your best triathlon', fink's 'be iron fit', the program I spend £70 a month on are all variations on a theme.....
I do 14 - 20 hrs a week.
Don't leave it all to the 20 week program though. The fitter you are when you start it the better, (although the previous x weeks should not be 'training', just fun exercise
Finally consistency counts - I have a basic week, that I try and do week after week after week.....(with different interval sessions / swim sessions / durations each week).