A group of people will enter heaven and stay there forever. This entrance might be immediately after the judgement or after some interval. The other group will enter hell and stay there forever. So in respect to time there is no limitation. There is also no limitation in respect to the intention (the quantity and the quality). We cannot campare His rewards with the pleasurable things in this universe. According to the Glorious Qur'an there is whatever they like in heaven.
“Therein shall be what their souls yearn after and (wherein) the eyes shall delight.” (43:71)
“They have therein what they wish and with Us is more yet” (50:35)
Not only they can get and enjoy whatever they want, but also there are things which they were not able to conceive. We usually wish what we have seen or generally experienced in advance. For example, people like to have a big house (with a big garden in a size and with qualities which cannot be found in this world). But there are still some blessings in heaven which are not familiar to men so they will receive them without any previous want or request.
“So no soul knows what is hidden for them of that which will refresh the eyes; a reward for what they did.” (32:17)
According to traditions there is in Paradise what no eye has seen and no ear has heard and no heart has conceived (imagined). We cannot understand the torments either. The fire there is not comparable with ordinary fires. That fire burns the spirit as well as the body.
“And what will make you realise what the crushing disaster is? It is the fire kindled by Allah, which rises above the hearts.
Surely it shall be closed over upon them in extended columns.” (104:5-9)
Those who enter hell and suffer its torments wish to die. They think in this way they can get rid of the torments.
“And they shall call out O Mahk Let your Lord make an end of us. He shall say: Surely you shall tarry. “(43:77) “Then therein he shall neither live nor die. “(87:13)
Whenever the fire bums their skin, Allah renews their skin to suffer again: “So often as their skins are thoroughly burned, We will change them for other skins. “(456)
Listen to Imam ‘Ali (a.s.) in his prayer when he says: “O My Lord! And You know that I cannot endure the tribulations and punishments of this world and whatever ordeals happen to its inhabitants, while they are not so difficult and so long. So how can I endure the tribulations of the Hereafter and its great ordeals, while they are very long in their time and endless and their sufferers are not given any respite, because they are from of Your anger and vengeance and discontent and These cannot be withstood by the heavens and the earth.