Personally, I wouldn't persist with it, no. But I am not a fan of controlled crying, which is essentially what you're doing.
What I started to introduce at nap times and then bed times was a harmless reason I needed to leave the room. We dry our clothes on airers on the landing, so I started to settle my twins in their beds, the say "I'll just be on the landing. I need to fold those clothes." Then leave for a few minutes, while still singing and shushing so they could hear me. I popped back after a few minutes, stayed a few minutes, then went to "fold some more clothes".
Eventually they started to trust that I was just going or a few minutes, that I wouldn't go far, and that I'd be back in a minute. The gaps between returning could be stretched out, and they don't bat an eyelid when I leave now, as long as I explain that I'm just going to fold clothes or go to the loo. I still sit with them for a while after lights out, often until they fall asleeps, but if it's taking too long I can normally go and fold some clothes eat my dinner.
At 23 months, I think your DC is old enough to start to understand where you say you're going, and learn to trust you'll come back. Keep singing for the first good while, so he knows you're close by.
Good luck! And if he naps in his cot, start at nap time because you're both in a more understanding and patient mood in the day than at bedtime 