Stock market investments

IRS requires details of every sell transaction to be listed on Form 8949,
or on your own forms (e.g. consolidated 1099-B) which have the same information and in the same manner as Form 8949.
Either way, if you choose to summarize, you have to mail the transaction details to the IRS within three business days of IRS accepting your tax return.
Exception: if you summarize Category A or Category D, Form 8949 is not needed for transactions without adjustments. No mailing is necessary. TurboTax won't ask you about wash sales if you don't check the box.

as an active investor, be aware that your category Box A sales without adjustments do not require Form 8949, so there is no reason to import or key in those transactions.
instead use the "enter a summary" option to put your numbers on Schedule D Line 1a.
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If you have wash sales, it gets more complicated since those adjusted transactions have to be itemized on Form 8949 and the summary totals adjusted accordingly.

enter the wash sales on Form 8949, then use the subtotal results on the bottom of that form to know how much to subtract. Be sure to NOT check the adjustments box in the summary window. TurboTax won't ask you about wash sales if you don't check the box.
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Alternatively, if entry of Wash Sales is too tedious,
summarize and check the box for adjustments and enter the disallowed amount.
The summary will go on Schedule D 1b.
You will be making the mail-in election.