True but you should always consider what more experienced people can offer.
Some kind of issues do not show up immediately, but will eventually happen with time so when you do a thing you better do it well.
Removing the rotor is just a matter of unscrewing 1 screw after all
@domiffm made valid points:
1- uneven oiling/greasing can cause excessive wear on parts that didn't receive enough lubrication.
2. Putting oil in the wrong spot without properly distributing it and cleaning it might cause the oil to go in unwanted places inside the movement.
3. Please check carefully maker specifications on which oil to use. Other lubricants might work but they can leave residues or decay with time. You can easily find this info by googling ETA oil chart with your movement ref number (e.g. 2836).
Happy learning!