Does it make sense to change bit diameter to save time on the same job?

Hello all,
I’m about to cut pieces in a 18 mm (about 3/4 inch) plywood, that includes some letters and signs to engrave. The signs are small ones, so I shall use a 3 mm (1/8 inch) bit for these pockets. But as I read “The general rule is that you need to cut in depth half the width of the cutting tool you are using”, I want to use then a 6 mm or 1/4 inch bit for cutting profiles, to be able to cut deeper in one pass.
That means: open a file containing the first g-code, then tell Maslow to go home, change the bit, recalibrate Z axis, open a second file containing the 2nd g-code. Maybe half an hour for these additional operations, but maybe hours for saving multiple passes (12 passes with 1,5 mm depth = 6 passes with 3 mm depth). G-code simulator indicates me 5h34m with a 3mm bit!
What do you think about it?

Do some tests and see how deep you can go in a single pass with decent quality. The bits diameter is only a guideline. Not a ridged rule

I think it could take a long time to cut a pocket with a small bit, it cuts a narrower path as well as less depth. It would be worthwhile to cut them separately as you suggested.

Ok, @blurfl, so I’m going to choose the little bit for the precise engraving then the biggest one for cutting around. I’ll have to be agile with MakerCam!
@Metalmaslow, I do not think I can significantly increase performance by changing the recommended values, In any case, I could’nt divide the number of passes by 2.
Thank you both for your answers!

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