The big assumption there is that the delay is only due to Sierra working multiple projects, not the planning of content, writing (including multiple paths that weren't in NN, not counting the endings), any art creation (including both scenes and new assets like maps, backgrounds, item images). I personally have no idea what the split is in their work on the game, but working with multiple people is generally slower than solo, since while you're waiting to hear back from other team members you may not be able to continue work and discussing with the team rather than directly progressing. On a solo project, you only have to worry about yourself getting content in, so it can go faster and, quite possibly in this case, be worked on while waiting on others.
But, as has been said before your choice if the delay between updates is a deal breaker.