When I started with particle physics experiments back in the '70's, there was a large number of independent experiments gathering data and slowly building up what is now the mainstream standard model. The number of authors in the papers at the time was order of 20, and many such experiments could be carried out by the hundred of groups studying the scattering of particles in bubble chambers and publishing the results. Now high energy physics papers are signed by thousands.
The particle data group laboriously added the statistical and systematic errors correctly of each experiment and came out with the results , changing continuously over the years. The only consensus is that the errors , statistical and systematic, should be smaller than 5 sigma for the valid experiments. As an example look at the rho decays and how the errors are calculated at page 4.
As larger and larger expensive instrumentation became necessary to gather more knowledge of the reactions, the groups became larger. The number ofthe same type of experiment at LEP was 4 exactly so as to have 4 independent confirmations for measurements, in order to reduce the possibility of systematic errors entering in the calculations. For LHC it is two, for the same reason . Then there are the independent experiments in the US.
Are today experiments under the high level of accuracy and complexity presented more prone to errors and false conclusions?
The results of the current experiments are scrutinized by many people ( remember the thousands of authors) , the errors calculated to the best of their ability, and if discrepancies are found in errors between independent experiments a lot of thought and effort go into trying to resolve mathematically the errors, before declaring new physics.
The OPERA result of super-luminal neutrinos, for example, is not validated by other oscillation measurements and the experiment itself found two possible systematic errors. Here is the history.
However, the ICARUS collaboration, which operates another detector in the same neutrino beam, analyzed its own data to show that there was no sign of the energy loss required by the Cohen and Glashow mechanism, a significant blow to the experimental finding.
Finally, in June the OPERA collaboration completed their own follow-up measurement with the fiber-optic connection fixed. The team found a speed consistent with both the light-speed limit and results from three other experiments using the same neutrino beam. From start to finish, the whole story took a bit under nine months, at the end of which physics was returned to the status quo.