One of the things that helps when you're developing your own projects is that you can single-handedly decide to ruthlessly cull parts of the project that take lots of time but provide little value, and you (probably) have decent insight into what those are. You're also probably not at a scale where doing certain really crappy, slow parts of the job can pay off, so you can skip those.
Default form elements with some basic, nice styling to fit your theme? Form done in one hour. Special snowflake version of the same thing from the design team, which has no idea what the platform can and cannot easily be made to do, but the client is absolutely in love with? Two days, a third party dependency or two, some extra environment-specific bugs to track down later, and generally increased fragility (so more time lost in the future). This has slowed you down now and increased the resources required for the project indefinitely. But the client looooooves it.
Support Android pre-5.0, at the cost of 20% more development time, a pile of extra bug reports, an uglier, harder-to-maintain codebase, and a much much longer testing cycle, for a side project? Hell no. Client says that will cost them $4 million/yr not to support those? Ugh. FINE.
Default form elements with some basic, nice styling to fit your theme? Form done in one hour. Special snowflake version of the same thing from the design team, which has no idea what the platform can and cannot easily be made to do, but the client is absolutely in love with? Two days, a third party dependency or two, some extra environment-specific bugs to track down later, and generally increased fragility (so more time lost in the future). This has slowed you down now and increased the resources required for the project indefinitely. But the client looooooves it.
Support Android pre-5.0, at the cost of 20% more development time, a pile of extra bug reports, an uglier, harder-to-maintain codebase, and a much much longer testing cycle, for a side project? Hell no. Client says that will cost them $4 million/yr not to support those? Ugh. FINE.
And so on, and so on.