If you're using colour to bring out the important details then it's definitely a route to take. There are other options like the first [few] page[s] of a chapter can be in colour like you see some comics do. Or when the page enters an important scene, usually full page spreads, you can use that time to bring out the colours as well.

I don't know how long you plan on making this web-comic but there is always the option that you can return to previous pages to finish colouring them or if you plan on specific panels to have colour you can return to previous pages to apply that to them as well so that it's all consistent. Basically all I'm saying as this isn't permanent. You can even take the approach that you leave them like this but if you plan to sell them in book format you can change things around to your desire so that it's all consistent in publication.

I hope you're not discouraged by the critiques provided to you by the two reviewers. They have solid advice, which will only help you to grow as you continue to work on this project of yours.

All the best on this. c;