The dollar can be used once a day. It has to be a dollar’s worth of a product, service or use of a product. For example, A dollar’s worth of a $100 TV would be the life of the TV divided by 100. You would get to enjoy the TV for that amount of time. The product or service is instant and doesn’t require any preparation. It just appears and disappears. Or you could have a TV permanently that is worth one dollar.
You can have one dollar’s amount of gold to keep forever or you can have any amount of gold for one dollar’s worth of time. It would depend on who you are ‘renting’ the gold from. If they say for a dollar you can have a pile of gold bars for X amount of minutes and then you give it back etc. You ask the magic dollar and out comes a ‘Spyro-esque’ Moneybags character lol. He might only let you touch the gold if he is stingy. The TV metaphor assumes the average life span of a TV these days. Or that particular model. So for a 1K TV, it would be a fraction 1/1000 of that TV life span.