vyvanse lasts a loooong time. A solid 10 hours before you sleep. At 8 or so you might think you're ready to get some shut eye, and the next thing you know you're at hr 12.
As for tolerance, the first day you'll be buzzin' pretty good if you hit the right dose (normally at least 50mg for a solid speed) but by day 2 you kind of get used to it. It's a super smooth drug
so you'll still be speeding, but won't have that geeked feeling that aderall would give.
When it comes to re-dosing, waiting at least an hour for your lysine enzymes to keep up is best. If not you hit a ceiling dose, wasting product. So start decent, then small doses spaced apart instead of a good dose, wait, good dose.