I generally go to confession by appointment, so I am there on Saturdays only on rare occasions. I’ve never gone on Saturday and been alone, though. (First Saturdays seem to be the most popular, for obvious reasons.)
Also, while I learned from the Baltimore catechism that one must receive the sacrament once a year, I know of people who think that one must only go once a year if one has committed serious sin–and that list has also been pruned down considerably in their minds from what we learned as kids. My own aunt actually told me, “Oh, nobody goes to confession any more.” That’s so unfortunate.
Still, if one only does what is required and does not commit a serious sin, that would put them at Church over 50 times a year with only one confession. Confession services during Advent and Lent are popular at our parish, too. The local pastors have several services (one per parish per Advent or Lenten season–lots of choices) where there is a group liturgy for examination of conscience, and then there are six or ten or so priests there to hear private confessions. Every time I have gone to one of those services, the lines have been very long.
My pastor is constantly using his homily to invite people to confession. I do not know a priest who would not like more people to come more often, to have a deeper prayer life, and to participate more fully in their parish. Nevertheless, the mere fact that there are not more people there on Saturday does not mean that the people you see receiving Eucharist on Sunday are receiving unworthily. That, we can’t know. The very fact that we wonder about it, though, is not a particularly good sign concerning our own spiritual health. We have to be very careful.