The same happened on this one too, wherein the block only contained a single transaction for the block reward. Idk if this is possible to do on a cumulative manner, though one thing I know is that it wouldn't be beneficial for the miner (in terms of profits) and the network (in terms of included transactions in a block) in the long run.
It's not weird if time interval time between blocks is less than a minute, especially because it's mined few years ago when bitcoin is less popular and a transaction need few seconds to propagate/received by all nodes.
smallest block i mean block without any confirmed transaction rather then coinbase, so any block without a transaction are counted as same