He said feedback from club doctors suggested the new rule was allowing them to make assessments without adversely affecting team performances.
"[That] is what we wanted, because we did not want them rushed or under too much pressure in the context of what is going on in the field of play," Dr Harcourt said.
The AFL Commission approved the introduction of the concussion substitute rule just days before the opening game.
The late call concerned some coaches but the decision coincided with the release in March of the Consensus Statement on Concussion in Sport.
The rule allowed for a player who was being assessed for concussion for 20 minutes to be temporarily replaced while evaluation took place.
Harcourt said that rule, combined with other initiatives such as the use of video technology to assist with assessments, was a positive development.
Carlton's Mitch Robinson was subbed out of the game against Richmond in round one, with the Blues consulting the footage as part of the assessment.
Harcourt said AFL medical officers received the SCAT evaluation results after each assessment and there was additional scientific evaluation of the effect of the knock made after the game using vision and other data.
He said the information was used to ensure compliance and to assess what was being done well and what could be done better.
"We're always going to have issues that crop up because concussion is not an easy diagnosis in some cases, but so far, touch wood, there hasn't been [an issues], which is different from last year," Harcourt said.
Seven players have been subbed off for concussion in the first five rounds while Melbourne's Rohan Bail was taken off and replaced for the 20-minute assessment against the West Coast Eagles. He returned to play.
Other players subbed out because of concussion have been Collingwood's Ben Reid, Fremantle's Luke McPharlin, St Kilda's Jack Newnes, North Melbourne's Majak Daw, Eagle Matt Priddis and Adelaide's Luke Brown.
On three of the seven occasions when a player has been replaced because of concussion, the team has still won.
Both McPharlin and Priddis were subbed out early in the game and their team lost after conceding huge leads.
