One thing that could be to your advantage over the summer is that, at least for the summer classes I've taken, the class size is significantly smaller. For example, the general chemistry sequence at my university typically had 200+ students, whereas the summer version I took (same class, just condensed timeline) had about 40. So while there certainly was less time to connect than if you had the full year, the professor also has more opportunity to engage in personal contact during class due to the class size - mine knew everyone's name by the end of the first week, something that just can't happen in a large regular semester class - and office hours are significantly less crowded, again due to the class size. I actually found it much easier to build a strong connection with my summer professors than during the school year, simply due to the smaller professor to student ratio.