Maybe this question belongs in another section but I'll ask here first. I'm in the process of ripping up a tile floor in the bathroom of our 1950's home. The tile isn't original to the house and under it I found the tile was set on what appears to be 1/8" hardboard over 3/4" plywood. There was some water damage to the plywood, so that went too.

Under the plywood and over the original tongue and groove, individual board subfloor is 1x lumber laid flat like sleepers in kind of a grid. The wood doesn't appear old enough to be original and the workmanship is kind of sloppy. My initial thought was that the bathroom had some kind of wet bed and the previous owner had just used the 1x material to "fill in."

What has me confused is that these 1x's continue under the strip oak flooring in the hallway. My construction experience is limited but something just doesn't seem right? Would you normally lay 1x under strip flooring and over the subfloor?