No hole punching if mailing to USCIS service center but I-751 should be mailed to a lockbox not service center so they recommend fasteners or heavy clip and sticky tabs.
https://www.uscis.gov/forms/filing-guidance/tips-for-filing-forms-by-mail
In preparing your packet, remember:
Do not use binders or folders that we cannot easily disassemble.
Do not use heavy-duty staples. Instead, use fasteners or heavy clips to hold together thick or bulky applications or petitions. Two-hole punching the top of the material for easy placement in the file is appreciated. Note: this is only applicable when submitting filings at a USCIS lockbox location. We recommend that you do not use fasteners, hole punch, staple, paper clip, binder clip, or otherwise attach documents to one another when filing directly with a USCIS service center as that may cause delays in scanning the documents into the electronic database systems.
Sticky tabs assist in locating items listed as attachments. For easy filing, place the tabs on the bottom of the page, not the side. Note: this is only applicable when submitting filing at a USCIS lockbox location. We recommend that you do not place sticky notes on documents when filing directly with a USCIS service center as that may cause delays in scanning the documents into the electronic database systems.
