Can I improve GPS reading accuracy with 15 minute hangtime, and taking the average?

Imagine i need to physically mark 4 corners of a field as exactly as possible, on known coordinates. Normal GPS isnt that accurate and i dont have the ability to use RTK.

Could I let the drone hang for 15 minutes and then take the average of all GPS readings that i receive in that time, so as to probably be more accurate in my marking?

Is there any clever way to do that? Like an extreme ‘glitch’ handling, it flies on a ten minute average reading just for that corner, something like that.

Thanks!

Here3 gives RTK

I doubt it would increase any accuracy over time. Here3 is a great option with ublox M8P module for the price of M8N. Also gives RTK option.