I only use roboadvisors and do not intend to adopt other investment methods as I am busy working and studying, will using only roboadvisors be enough?

Using roboadvisor is a good start!

You may wanna read up more during your free time and invest yourself to get higher returns if you’re willing to take the risk! :)

When it comes to investing, there is not such thing as 'not enough' or 'enough' it all boils down to what's your end goal? If you ask me if it's enough for retirement, maybe not, but is it enough for the next 5-7 years? Probably yes.

This approach fits your current lifestyle as investing requires lots of research and conviction, this way you can at least ensure decent appreciation of your money in the short term.

But in long term I would suggest that you look at other forms of investment that can further accelerate your wealth.

Investing is about ideology, not action. That said, you should stick to 1 technic and stick with it until you amass a capital of around 100k~. Then you can look into multiple sources like a mix of asset classes.

I'd suggest sticking to 1 robo to build until around 50k. Use that 50k to do a one-time investment in an ETF of your choice (eliminates the yearly fees). Then use robo to continue amassing your wealth.

I am feeling perplexed reading the other respondent answers. Being at 22 years of age you just wanna earn some extra money and make your money work for you while you study and do your higher priority stuffs. That's it if I know where you are coming from.

First question: I consider this as passive investment.

Second question: you are working and studying, so confirm no time to DIY on your investing strategy. Suggest yes as you said Robo is the way. Looking at your current situation you are not full time working or supporting a family or retiring. Forget about all those what buy low and sell high, Bitcoins etc.

Third question: Another 5-7 years means you already have a timeline. 5-7 years to grad from school and start your full time working career? If yes, Robo is a side hustle for you to earn some extra money before you hit your timeline.

Forth question: suggest to stick to one Robo instead of using two. Less is better than more. You are putting in 300 SGD per month which is not alot. Focus on one and try and get the maximum output instead of doing two.