The HSA form I used when I had an HSA allowed you to specify either a single date, or a range of dates, or to specify "multiple dates". In many cases even a simple thing could be spread over multiple days: lab work, an x-ray, dental work. The reimbursement claim form could also handle multiple medical expenses on a single form. I would include all the items from a single EOB onto a single claim form.
In my experience I also wanted to wait for the EOB (Explanation of Benefits) to be generated by the insurance company before making a claim. This was for two reasons: to show the final amount after the insurance company processed the claim, and to prove that I wasn't claiming funds that were also being paid for by the insurance company.
I also found the paperwork was simpler when the funds were being sent to the medical providers office, versus reimbursing me for expenses I had already paid. Some providers were happy with that arrangement, while others wanted me to use my medical expense debit card at the office or a regular credit card and then have to get a refund from the provider, and then put the funds back into the fund, or get a check from the fund.