FDA guidelines allow volunteer whole blood donations every 56 days, plateletpheresis donations twice a week up to 24 times a year, plasmapheresis twice a week (as long as total protein and immunoglobulin levels remain adequate) and double red cell collection by apheresis every 112 days.
In general, most donation centers allow you to give whole blood every 56 days, which equals about 6 times a year. However, it's important to follow the specific guidelines of the donation center you are visiting, as policies may vary.
2 times in a year
Once.
250
Normally once.
twice
2
anytime it wants
Small mammals like mice and shrews can give birth many times in a year.
Usually only once.
Two times a year, leading to over 20 piglets a year, 8-12 per litter.
We can give iit-jee 2 times. Once after passing 12th class, and the next year!