Incubation period for Omicron may also be shorter, which could worsen things quicker and also affect optimal testing windows...
How Long Does Omicron Take to Make You Sick? (msn.com)
"Estimates for this exposure-to-symptom gap, called the incubation period, clocked in at about five days for Alpha and four days for Delta. Now word has it that the newest kid on the pandemic block, Omicron, may have ratcheted it down to as little as three."