If you aren't seeing him at least twice a month, it isn't a relationship. Overall, there are very few exceptions to this. Simply put, if a man loves you, he wants to be with you- not just via skype, text, etc. Actually, keeping up on Skype, texting, and phone calls don't mean much. The only thing that matters is if he's asking you out on dates in advance. He could simply be calling or texting you if he's bored at work (or in general). So, don't read too much into it.
Unless one of you has to work or has custody of children every other Saturday, he should be seeing you on Saturday nights. He shouldn't be skipping Saturday dates unless there are extenuating circumstances (as mentioned). Saturday is a universal date night. While you can miss a Saturday night, he can't.
There are a few exceptions to this though. For example, if he is on a military deployment, studying abroad, away on a business trip, or frequently travels for work, there may be times where you go for significantly long periods of time. This is okay. But, besides that, it isn't acceptable for him to not see you. Even if both of you are in school in different states, there's no reason he can't see you at least a few times a month. For the first few months, he should be coming to you 100%. While you can visit him once for every three times he visits you, he needs to be doing the bulk of the legwork. When you visit, he should still be taking you out, paying for everything, and picking you up to and from the airport.
For some younger couples, you may be thinking "What if we can't afford it?". This is a valid argument but, here's the thing: men are protectors and providers by nature. If they love you, they have no problem paying for dates, traveling to see you, and more. Simply put, they make it work. However, you may be part of a really young couple. I've been in this position before and it isn't fun. However, if they're that serious about you, they will come to you a majority of the time. Otherwise, they aren't that serious. Sadly, most of the time, Long Distance Relationships aren't that serious and don't pan out. I have seen very few work out long term and, even out of those that do, very few seem happy.
If you want to see what not to do, watch 90 Day Fiance. Since the first episode, this show has been a guilty pleasure. There are a few couples that get things right- Kirlyam and Alan, Amy and Danny, Noon and Kyle, Aleksandra and Josh, and Alla and Matt. In my opinion, these are the only couples that will work. I predict that only about a fourth of these couples will last long term. However, all of the couples are long distance and the bulk of them have some pretty serious issues. Some break up during the course of the show. But, if you dig deep enough, most of them are either divorced or having some serious issues. Plus, keep in mind that even if a couple stays married (or gets married in the first place), their marriage may not be a very happy one.