A charge is not a deduction
A line on a bank statement shows that money moved. It does not show what it was for, and the business purpose is the part that makes it deductible.
The burden of proof is on the taxpayer. An expense with no record behind it is not a contested deduction, it is an absent one.
This matters most for the expenses that look personal from outside: a restaurant, a hardware shop, a flight. The statement line is identical either way.
The $75 line
Below $75, a documentary receipt is generally not required, though you still need a record of the amount, date, place and business purpose.
At or above $75, and for lodging at any amount, a receipt is expected.
The threshold is commonly misremembered as permission to keep nothing under $75. It is permission to keep no paper, not permission to keep no record.
Mileage is its own standard
Publication 463 asks for date, miles, destination and business purpose, per trip. An annual total is not a record, however honestly it was arrived at.
Commuting between home and a regular place of work is never deductible, whatever the distance. Travel between two work locations generally is.
You choose between the standard rate per mile and actual vehicle costs, and the standard rate already includes fuel, maintenance, insurance and depreciation, so those cannot be claimed on top.
Why March does not work
Reconstruction in March fails in two directions at once. Deductions are missed, because nobody remembers what a $43 charge in June was for, and deductions are claimed without support, because the charge looked business-shaped.
The first costs money quietly. The second is the one that does not hold up.
Recording at the point of the charge takes seconds and is the only version that is both complete and defensible.