Hi ​@tecnologia,

I believe our support team will be able to help you best with these questions. I have opened a ticket on your behalf and copied the email you have registered with here on Planet Community. 

Adding some documentation here to the thread:
Processing Units 

To others who have the same/ similar questions:

Processing API
Is there any way, such as a REST API or endpoint, to retrieve only the dates of the images?
The Catalog API is the recommended way to search and discover data in Sentinel Hub. It implements the STAC (SpatioTemporal Asset Catalog) specification, providing detailed geospatial information about available scenes, including acquisition dates and times. More information about it at: https://docs.sentinel-hub.com/api/latest/api/catalog/
 

Some Sentinel-2 L2A images, depending on the region, may have variations in temporal resolution. What is the explanation for this?
The variations in temporal resolution of Sentinel-2 L2A imagery across different geographic regions can be attributed to a combination of factors. The inherent geometry of the Sentinel-2 mission's near-polar sun-synchronous orbit leads to increased overlap of satellite swaths and thus a higher revisit frequency at higher latitudes compared to the nominal 5-day revisit time at the equator. While the mission employs a systematic global acquisition strategy, regional data availability can be influenced by specific requests from Copernicus Services or member states. Furthermore, practical limitations such as cloud cover and the availability of sufficient solar illumination, particularly at extreme latitudes, play a significant role in the frequency of usable L2A image acquisition. You can find more information about Sentinel-2 coverage at: https://sentiwiki.copernicus.eu/web/s2-mission#S2-Mission-Geographical-Coverage
 
Processing Units
Do you know if PUs vary when using the same request parameters but changing only the area? If there's no variation, how many PUs does it typically consume, for example, to process the NDVI of a 50-hectare area at 10-meter resolution?

PUs will vary depending on the size of the area. Please note that the minimum value of the multiplication factor is 0.01, which corresponds to an area of 0.25 km² when using Sentinel-2 data at 10 m spatial resolution.
 
For a 50-hectare (0.5 sq km) area at 10m resolution:

• This would be approximately 71 x 71 pixels

  Parameter	Quantity	Multiplication  factor - NDVI
  Output size (width x height)	71 x 71 px	0.0192 = (71 x 71) / (512 x 512)
  Number of input bands	2	2/3
  Output format	16-bit tiff	1
  Number of data samples	1	1
  Orthorectification	No	1
  	Total	0.0192 x 2/3 x 1 = 0.0128 PUs

   
  
  ​​​​​​​Please use the link below to learn how to estimate the number of processing units (PUs) needed and to see examples of cost calculations for Sentinel Hub requests: https://www.sentinel-hub.com/faq/how-can-i-know-how-many-processing-units-i-need/