How long can one maintain a pump? Is there any benefit to maintaining one for a long time or is it just extra strain on the heart? I was stuck at the gym longer than usual last time, i had long finished my workout but figured i may as well keep lifting until i could leave...ended up lifting for like 2 1/2 hours and was barely able to lift anything lol. But i wondered is there any benefit to maintaining a pump for extended periods of time? Or once you exert your muscles to a point(a normal workout), will lifting further do nothing more than wear out your joints?
Also, do you think there is any benefit to doing a certain movement until pumped many times a day? For example doing a movement in my office to work my bis/side delts until pumped every hour or so(

) or is it pointless and less effective than doing a single typical workout for the same muscle groups?