Is there a way to make sure my custom coding isn't affected by the new features?

hello. I am currently a user using the 7.1 template. I feel stressful whenever a feature is automatically updated. Because I have to change the codes every time. If I create a new template with 7.0 or 5.0, won't there be any inconvenience as the features will be updated?

For example, things like new form design format.
Any helps would be appreciated! Thanks.

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