Opponents in our rec league used a 5 man against us 4-6 times last season. It only "worked" once, but not because we hit the outfield gaps. The one time it "worked" was a game where we just hit the ball right at the fielders, both infield and outfield, and the 5th infielder really didn't affect that. It didn't work against us in the other games because they obviously hadn't practiced it. We beat it by (unintentionally) hitting grounders between the infielders, who just watched the ball go by rather than run into each other. Most of the teams that used it, did so to be trendy, or because their infielders had no range whatsoever, although they could/would/should have fielded the balls they watched go by in the 5 man had they been in a 4 man. Most of these teams didn't have the outfielders to make a 3 man outfield work.
The first time I played against a 5 man was years ago before it was a thing. It was a weird game that shouldn't have been played in the first place. Both teams were missing a lot of players. All but one of ours was on our roster, but we were missing several starters. I think I was hurt and played 1st instead of SS. At least half of the guys on the other team weren't on their roster. The SS and MI were ringers brought in from outside our league, and way better than anyone on their roster. On top of that, the field was so muddy, we shouldn't have been playing on it. The 3rd base line looked like a snake that was a good 3 feet from the innermost to outermost points due to the mud. It was hard to tell if the 5 man or the field was the bigger factor. We lost a close game, but I always thought my starters would have beaten that 5 man on a dry field.