The We Watch group has called on the Election Commission (EC) to hurry up with the vote count and officially announce the poll results soon so the new government can be formed and get to work quickly.
The group of young poll monitors announced on Tuesday the EC should not dawdle but make the official poll results known much earlier than the deadline.
The law permits the EC to release the official poll results within 60 days of the election.
Pongsak Chan-on, the We Watch director, said the 60-day window could delay the formation of the new government and hold back the country's affairs.
It would be best if the EC were able to wrap up its work and get the results out within seven days of the polls, he said.
As of Tuesday afternoon, 99% of the 39 million votes cast nationwide had been counted, according to the EC's official website https://www.ectreport.com/overview
The We Watch group said it had sent members to keep an eye on many polling stations across all 77 provinces on Sunday.
Krit Saengsurin, We Watch's information officer, said the group did not end up encountering any "critical" problems with the election.
However, Mr Krit said the group had found shortcomings such as a lack of facilities for disabled voters at polling stations in provinces including Chumphon, Khon Kaen, Ubon Ratchathani and Bangkok.
We Watch added there were few facilities for wheelchair-bound voters and a lack of machines to help those who are blind or deaf in handling their ballots.
On the whole, the group said it was also unfair that the law omits the voting rights of monks, people with mental conditions and inmates.
In addition, the allocation of different campaign numbers for the two ballots -- one for selecting constituency candidates and the other for parties -- was also confusing, according to We Watch.
Also, the names of people were mixed up in the house registrations, and some voters' names have remained registered at their old houses despite the data transfer having been completed.
The group has vowed to keep on monitoring the work of the EC until the new government is officially up and running.
