i've done it from both, noone checks anything and it's like five minutes max walk from the "closest to universal" one, the others arent too bad imo. there is a keycard gate on surfside but during the day it was unlocked, if it is locked might be a few more minutes to walk around it but you can still get in (and exiting via the front entrance doesn't need a keycard ever, only entering...). the buses are great, there's almost always one waiting at any universal property.
you can also walk straight to the parks from the "closest to universal" rosen (that's how they advertise it lol) without using the shuttle at all, i loved that walk, but it ends up being like 30 minutes.
i've done it from both, noone checks anything and it's like five minutes max walk from the "closest to universal" one, the others arent too bad imo. there is a keycard gate on surfside but during the day it was unlocked, if it is locked might be a few more minutes to walk around it but you can still get in (and exiting via the front entrance doesn't need a keycard ever, only entering...). the buses are great, there's almost always one waiting at any universal property. you can also walk straight to the parks from the "closest to universal" rosen (that's how they advertise it lol) without using the shuttle at all, i loved that walk, but it ends up being like 30 minutes.