Independent unionist MLA Claire Sugden has hit out at the five Executive parties for not planning in advance for the return of devolution.
The former justice minister said that with MLAs now having to consider 600 statutory rules, it was limiting how often the Assembly could sit.
She said there was now only one plenary session a week which disadvantaged MLAs from the smaller parties and independents like herself.
Ms Sugden said: "The suspension of devolution for three years has meant a huge build-up of statutory rules that have to be scrutinised by MLAs and respective committees.
"Legally, these rules must be considered within 10 plenary days.
"The only way to realistically do that is to reduce the number of plenary days.
"So rather than the Assembly sitting twice a week, as it used to, it is now sitting once a week.
"MLAs are losing our voice in the Assembly because of the political intransigence which left us without government for three years."
Ms Sugden said that the big parties were aware in October that Stormont would face this problem if devolution was restored.
"They could have asked the Secretary of State to change the legislation at Westminster to give the Assembly more time to consider the statutory rules," she said.
"But they didn't so we now have to focus on cleaning up the mess of the past.
"It is very frustrating because people want to see MLAs sitting in the Assembly, and that will now be happening only once a week for the next few weeks.
"Some of us had hoped to hit the ground running, and that is what the public wants too."
The Ulster Unionists' Roy Beggs expressed concern that MLAs on committees had been given too little time to scrutinise statutory rules.