What happens when we reach the end?

https://newsletter.bitcoincollective.co/p/tomatoes-powered-by-bitcoin

I have hundreds of transactions on a couple different exchanges from DCAs (don't worry I move it over to cold storage). I haven't sold any bitcoin yet, but I was wondering how I would determine the cost basis in the event that I wanted to sell a portion of my stack. Was hoping to learn through other people's experiences - here are the questions I have and feel free to add on any advice/tips. Thank you!

1. Do people keep manual spreadsheets of all their transactions with different exchanges?
   
2. Do you determine the overall cost basis of your stack and use that for the portion you sell? Do you use LIFO, FIFO, Special Identification, something else?
   
3. Once you sell a portion of your stack, how do you redetermine your cost basis accurately?

Bitcoins price is the same as a year ago. 1 year ago strategy owned 190k. Now they own 500k more than that. If you’re letting your coins go, you’re just giving it to the institutions. Hodl.