Yes, being overbowed often causes shooting left. The reason is that you often short draw, slowing the arrow which then does not flex enough and flys left. Remedies are: 1, a lighter bow; 2, a longer draw or 3, heavier arrow heads, by two or more steps. Number 1 of course is best, but if you are young and sturdy developing the strength for number two is possible. It is not wise as 50 pounds will kill most anything in North America and few men, very few in my experience, become really fine archers with as heavy a bow as 55 pounds.
The problem is not pulling it for a few shots. The problem is pulling it for the many times a week, month and year it takes to get really good with it.
It is possible to do most of your training and shooting with a lighter bow, 40 pounds or less, maybe 45 for a stout fellow, and become a fine archer, and then a month before hunting season carefully build up to 55 or more.
I have just done that again, in fact. But the first three weeks after I went up to 55 were a joke. Chums were telling me my arrows were wrongly spined and that my nock point and brace height were wrong. They weren't. In week four everything came together and I began to shoot that bow well so long as I did not shoot too many arrows in a day or week.
The need has passed after some fine hunts but no trophy and I am back to bows that weigh in the forties and that I can shoot well for several hundred arrows a week. Later I will drop to target bows in the thirties for the winter and indoor seasons.
Incidentally I am a sturdy fellow and can shoot much heavier bows; just not very often or very well. - lbg