Both partial or investing one time is a good way to invest in Bitcoin because not everybody can be disciplined enough to keep to investing partially. Some people are not good with money that they will use the money for something different than what they kept the money for therefore when someone with this type of habit has money to buy Bitcoin, they can go ahead and buy as much Bitcoin that their money can get them. The decisions we take today will be our saviour tomorrow because Bitcoin is not going anyway but it will be with us for a very long time. There are many ways to succeed with Bitcoin and buying them to hodl is the best way without having any specific way to buy Bitcoin. Many people choose to invest partially because it reduces the stress.
Success is not difficult, but it requires persistence and a willingness to act and all lead to making money from Bitcoin. Of course there are several approaches we can take, namely adopting a long-term strategy by storing Bitcoin well and we can expect its value to increase over time. However, everything must be prepared starting from capital, additional capital and being good at managing money as you mean above.