lvl 8 SS with int treads has about 750 MP. 12+52 MP per 100 units, so it costs about 390 MP (52%) to zip 600 units. That sounds like a lot! Until you realize he can sip bottle while zipping, to recover 70 MP (a little under 10% of his total mana.) Until you realize Soul Ring is 150 MP on demand with no health cost (because bottle heals it), and 150 MP is another 20% of his MP... he can recover basically half of his mana pretty much instantly, on demand, for no cost. Hence why SS can zip 600-800 units into a fight, pick someone off (max E build is popular because it's very mana efficient), and then still have enough mana on hand to zip 300-400 units away to safety.
Also worth noting that bottle restores even more than 10% mana per sip if he swaps to str/agi before sipping.