In my case, I chose writing a piece where each sentence must have a number in it. I've realised that doing this does indeed improve the quality of the sentences. It was a great exercise and I'm planning to use this when I begin my next longer work of fiction, mostly because in longer works the space actually removes constraint and, at least for me, leads to flabbier sentences.
Below is my piece: Five Blankets.
He murdered a man at twenty-four. In the prison where they sent him, he shared one big room with tiny windows high up near the ceiling that let in no breeze on forty degree days. Seventy men can make a mighty smell, he realised, a solid, alive smell that moved around and slapped you every now and then, reminding you about the seriousness of the situation. Though he was a murderer he had two non-murderer traits: a soft heart and the inability to identify evil.
That first night, he was given five blankets and told to find a space on the floor. Blanket number one, he rolled into a pillow. Blanket number two and three he folded into thirds and used as a mattress against the hard, concrete floor. He covered himself with blanket number four. Blanket number five he rolled up and lay next to him. The first night he pretended it was his long ago girlfriend, the girl who lived next door to them when he was ten, Carmela; Carmela made the night shorter. The second night, blanket number five was the woman he left behind when the prison doors shut behind him, the woman he’d murdered for; she promised good would prevail despite all evidence to the contrary.
On the third night, when everything became too real no matter how he twisted his mind, when seven men promised they’d “get him” before the week finished, when the bed bugs and the heat and the prison guards high with their small power picked and poked him until ignoring was not an option, blanket number five became his mother. He became her little boy, her three year old boy afraid of the monster rattling under the bed. His mother hugged him and all seventy men disappeared in the fierce light of her love.
His mother stayed with him until day thirty-two when Prisoner 538 tried to steal the rolled up blanket lying next to him. He couldn’t allow that, and with four blows and a kick, he murdered his second man, again in defence of the ones he loved.