The problem is in the cumulative light period if you do that. Say I like my tank having light from midday to 8pm at least (8h total period). My daylight is intense since 8am. If I keep tank exposed to daylight + my light period ---> 12h light period (8am to 12pm daylight + 12pm to 8pm PCL), not good for my needs in growth/CO2 use. If I still want my 8h period, I'll have to turn off lights at 4pm to have a total of 8h exposition. However, in summer here, daylight is intense till 8pm, so it won't work for me either.
Add to all this, changing artificial light period won't solve the issue of the exposition of organic substrate to daylight, which will cause algae on the substrate. No functional issues, but ugly to look at such a substaret visible layer. Usually, algae growing there are BBA as low CO2 is in substrate and they don't need much light at all to grow. In organic substrate I also noted BGA issues, which is a bigger problem as they tend to extend in water. Since I covered the substrate no more issues.
On my 60 gal, placed in a dark part, i don't have those issues.