Is it worth it to play around with rune pages or should I stick to guides?
Solution 1:
Apart from some runes which plain have no discernible effect for certain champion, most runes combos work - and just for the sake of learning how the runes look like and work there is some sense in at least having tried each rune a few times.
Beyond that, it boils down to how much better you want to become at your play style.
Because below a certain level of high-performance play which most players never touch, the runes have a much greater psychological effect than actual gameplay impact. If you deviate from things commonly understood to be effective in your Elo bracket, then just the fact that your teammates and enemies notice this deviation will hurt the rate at which you are winning games because of how attitude and focus have such giant impact in the majority of skill brackets.
If you still wanted to win the majority of your games, you would have to be better at what you are doing than the majority of players are at what they are doing. Thus it's generally much easier to stick to things most people expect to reliably work well (in League, generally called Meta). Delivering average performance with uncommon choices was a 5 percent point difference in win rate for me when compared to average performance with common choices. That is roughly what you would have to make up for. If there was a rune combo that had this much win rate difference for more than some specializes players, it would be considered "broken" and swiftly balanced away.
Since you generally learn the game better while you are playing close games (as opposed to a series of stomps), I highly recommend not trying to adapt too early - instead first trying to becomes reasonably good at things you will find in popular guides.
But if you already notice you tend to micro-optimize one particular champion and/or strategy where you quickly become much better than the average player, then trying out your own build & runes in that niche where you have a clear advantage and enough specific knowledge to actually utilize the minute differences between runes makes more sense.
Solution 2:
Really, Mobalitics is good, but you should probably spend the time to learn what the runes do, and that will bring you to being able to decide them on the fly.
Why should you spend the time learning them? Because well, even if Mobalitics or OP.GG gives you a rune combination, well if you don't know well what does those runes do you will not use them to their fullest and thus, making you be not a lot further than putting in random runes. Taking from what I know from OP.GG, those builds are also made for Plat+ players, that will know how to play optimally and use the runes to the most they can give them.
Also, Mobalitics doesn't usually consider against who you will be going, and if you play as a group, how the group will or not play around you. Learning the runes and knowing what combo works is good for that too because yeah, the mobalitics kit will be good generally, but going for a non-mobalitics build may help you in the particular matchup you are in.
To wrap my probably pooly made point: Using mobalitics is ok, but is not optimal. It will work most of the time, but there are so much variables in LoL that knowing how to switch your runes on the fly will be more optimal than using the premade build.
Using the mobalitics build is like buying a frozen pizza. It will do, its pizza, its edible, it feeds you. But it will never be as good as if you made your own, homemade pizza, where you control everything.