The "average" flyer if he covers the area of sport, 3 D flying, helicopters, pylons racing, and giant scale (55CC) will need 9 or 10 channels.
If you become a "Geek" working with scale or larger giants, then it may require require spare channels.
Best I did with JR radio with programming, had a twin engine transport start one engine, wait 5 seconds, and then the other started and then gave you back the throttles (called a sequencer) and the second sequencer either had a no brake, brake on, or a oscillating servo so when taxing, moved the plane at a fixed speed. Then you could reverse it so you landed, taxi back at fixed speed, lock brake, then you could flip a switch which reverse and shut #2 engine off, 5 sec and then #1 engine. That's what I used to do as a plane captain in my Navy day's.