Not sure if this is the right thread for it but tried googling and could only come up with something not relevant.
If I have the choice of dropping payroll biweekly over the full year into an HSA or just dumping the full amount into it all at once, assuming it hits the max allowable contributions either way, is there a reason not to do the latter?
My thought was that if its setup so that I only keep a small portion (next to zero medical bills really) and the rest goes directly into investments, having 12 months of +7k would net a larger benefit than it sitting in my savings account at some garbage interest rate, unless the options I have it in tank.
All the results in google just say to max it out before putting it into a 401k/ira/whatever instead of when within the year to max it out.
One benefit to bi-weekly, assuming the HSA deduction is coming from your companies payroll, and you make less than the Social Security maximum, is that you won't have to pay social security tax on the $7200. If you do the bulk 7200, you will be able to deduct the HSA from your wages, but not from social security wages when you do your taxes.
Otherwise its the same question people ask about maxing IRA on Jan 1st in something like index funds. Some years you win, some you lose.
I myself keep my HSA receipts and just pay for bills from savings. I don't plan on ever redeeming those receipts, but just a backup in case I need the money. I use to do a 60 day indirect rollover every January from my companies HSA, but I don't get that social security benefit anymore so I just contribute directly. Indirect rollovers are also good if your company HSA sucks and you have to contribute there to get matches.
See this:

How To Rollover an HSA and Avoid Trustee Transfer Fee
If you don't like the HSA your employer chose for you, you can rollover the money to a provider you like for better investment options.
I use Fidelity for my HSA which allows me to buy pretty much whatever.