I have seen a lot of games with lots of goals scored. It depends mainly on your opponent. If your opponent is a bot, or has an outfield player in GK position, you will notice a lot of goals. If your opponent is managed by a real person, it depends mostly on the quality of the team and the tactics used. A messy formation from the opponent does allow your team to score more goals. But lately, I have noticed a decrease in the amount of goals scored against teams managed by real people, which makes it more realistic. What I don't like is when your quality and tactics appear to be far better than the opponent, and still, your team fail to score a lot goals.
But still, I prefer the 3-5 goals, may be up to 10 if an outfield player is in goalkeeping position, rather the unrealistic 10+ goals that I have seen or posted by other members here.