What's the most efficient individual tax filing software for error-checked e-filing during peak season?

If you mean “most efficient” as in fastest, least hassle, and with solid error-checking for an individual return during busy season, the best answer is usually:

Best overall: TurboTax Online

• Strong guided interview flow
• Good built-in error checking
• Very reliable e-filing experience, even during peak season
• Best for people who want the software to do most of the work

Best budget-friendly option: FreeTaxUSA

• Also supports error checking and e-filing
• Much cheaper than TurboTax
• Good if your return is fairly straightforward
• Less polished, but efficient

Best for more advanced filers: H&R Block Online

• Good error detection
• Solid import tools and review checks
• Often a good middle ground between TurboTax and cheaper options

Recommendation

If you want the smoothest, most efficient error-checked e-filing experience during peak season, I’d pick:

TurboTax Online for ease and speed
or
FreeTaxUSA if you want the best value.

If you want, I can also give you a quick comparison by price, speed, and best use case.