I believe it will either reserve that space or use it when needed and besides, if you are stuck for 150MB that means your disk is too full anyway. With SSDs it's even less relevant because it has no specific area in which to place partitions. Even with HDDs, logical and physical partitions are not in same place.
I'm still looking for a way of preventing windows from splitting my ssd into several partitions, so if anyone knows how to stop windows from doing that, please post it in this thread, thanks.
If it's an OS disk, some partitioning (visible or not) is inevitable. One obvious is C:\ for OS/Windows itself, another one always first for BOOT sector, BOOT files and their copy, that's for Legacy BOOT. Another one for UEFI (EFI partition) if OS is installed that way. Only other partition that you can get rid of is Recovery partition used by Windows for automatic recovery but that one tends to show up with every major update also used for updates for keeping replaced files while updating. Order of those partitions (except very first one) may be different but are needed in any case.
All of those "necessary evil" partitions don't amount for much of space taken to bother with but their lack may have bad consequences.
Linux is even more demanding in making own partitions but that's more controllable during installation (if you know how).
Ditto @CountMike. I've installed Windows 10 on both clean drives and upgraded over previous versions, always end up with either 3 partitions or 5 partitions. My 5-year-old ASUS Desktop came with an additional partition, C: is 150GB and D: is 780GB on a 1TB drive, the other partitions are less than 1GB each.
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