no quick answer for that. you don't necessarily know how much liquidity is available to you at any time. One also imagines that at higher amounts the fees also go up. I wonder if there's already a website tracking all that.

All depends on how much liquidity you have, how much you're willing to take the slight security risks lightning can have for payments going through, whether you're using custodial lightning or not, etc.

Basically, no one can really answer the question for you