Irregular gaps between new hardwood flooring and old baseboards

Curious about how people would attack this. Just bought a new house and starting to get into some of the improvement projects.

Basically, the prior owners seem to have DIY-installed some new hardwood flooring in the finished basement. However, there are irregular horizontal gaps all around the edge, between the wood flooring and the old baseboards.

Most of the gaps with spacers are small (1/4 inch or so and in any case not more than 1/2 inch at most). There are plastic spacers left in many of these small gaps and I am guessing they are expansion gaps and the plan was to just run shoe molding around or something like that. Here are some pics of the smaller gaps.

But along one wall the gap is big—a full inch. It looks like they just didn't have room to put another plank and didn't cut one. Here are some pics of the large gap.

Curious how folks would go about fixing this up, particularly on the large gap wall. Do I need to basically finish their job and find the same flooring they used, cut additional planks, and fit them in with an expansion gap and then finish running shoe molding around the whole floor? Or is there an easier way to handle the large gap?

Thanks!