The closest trials have been deemed a waste of time or questioned by the clubs is when a star player has gotten injured and been ruled out for the season or a significant portion of the season.. There would be comments about are they still needed or comments about playing on the grounds that weren't NRL quality or harder due to the summer weather.
I'm pretty sure Stuart in his earlier days coaching questioned trials and threatened to skip them.
The clubs seem to have found a good medium with them now. Both in how they are scheduled with two trials a rest week and the season proper. Then also what they want to achieve.
- Star players get some match fitness in as their pre-season is often shorter.
- Fringe players get a chance to prove themselves.
- Recruits get a chance to build combinations with their new team mates.
- Players moving positions get game time to get used to the new position.
- Young guys get a chance against NRL level players. The club can assess if they are ready or not for first grade.
There is also a demand for them from the fans as we have seen the last few years where it has gone from one televised trial and finding streams to the trials getting televised.
The NRL have tried to add importance to them with the pre-season challenge concept. I'm not sure if that will take off or is really needed.