This is a VERY broad rule of thumb. The more consistent a player is, the more often they will play to their handicap. Players who are improving will obviously play to their handicap more often than a player who is getting worse.

To the OP, the system is based on turning in ALL rounds, competition or not. Only practice rounds are excluded. Personally, if I’m playing by myself, I usually consider that a practice round, since normally I might hit a second ball or re-putt a ball to see what went wrong or rehit a shot with a different club to see the difference.....stuff isn’t allowed in "real" stroke play. I normally exclude "vacation" golf, since we always make it a priority to keep it fun and enjoy the course and the refreshments. (ie....liberal amounts of mulligans and beers )

When our weekly foursome plays, we submitthe scores everytime.